Braunford LLP & Anor v Pierre Allain

This is my considered judgment on the first full case management hearing in this case. On 24 and 25 July 2025 I heard a number of applications and delivered two extemporary judgments: [2025] EWHC 1934 (Ch) on the defendant’s partly successful application for an extension of time for service of his defence and a successful application by the claimants for an expedited trial, and [2025] EWHC 1952 (Ch) on the defendant’s unsuccessful application for an anonymity order. This has resulted in orders dated 25 July (and sealed on 29 and 30 July) for expedition and directions, for confidentiality, and for a confidentiality club. The directions order provided for an expedited trial, to be listed in a five day window from 16 February 2026, with an estimated length of 8-10 days. It also provided for a case management conference on 18 September 2025 with a time estimate of one day to determine: (a) any issues between the parties in respect of disclosure; (b) any application made by the defendant to rely on expert evidence; and (c) whether the proceedings should be subject to cost budgeting (and if so, to list a costs and case management hearing).

That case management conference duly took place before me on Thursday 18 September, between 10.30 am and 5.15 pm. Mr David Craig KC and Mr Charles Ciumei KC appeared for the claimants (with junior counsel) and addressed the court. Ms Kendya Goodman (of counsel) appeared for the defendant. The disparity between the litigation resources available to the opposing parties was starkly manifested by my view from the bench: there were no less than eight people on the claimants’ side of the courtroom, with only two on the defendant’s side. It was part of Ms Goodman’s oral submissions that the financial asymmetry between the parties was matched by a similar informational asymmetry, which should be factored into the scope of the extended disclosure to be ordered by the court. Even though the court sat until 5.15 pm, not all live issues were able to be addressed in oral submissions. Nor was there any time remaining for me to deliver an extemporary judgment, or even to announce any decision on the outstanding issues. Given the order for an expedited trial, it is imperative that I should deliver this judgment as soon as possible. Given my busy judicial calendar, and the additional listing pressures resulting from the post-hearing announcement of the elevation of another of the Manchester Specialist Circuit Judges to the High Court Bench, this judgment is necessarily less fully reasoned than I would have wished. This should be borne in mind by the parties (and any appeal court). It should be read in conjunction with the parties’ detailed written skeleton arguments, and the full transcript of the hearing, all of which have been available to me, and to which I have referred, when preparing this considered judgment.

I can take the factual background largely from the agreed case summary. The defendant is a data scientist who had been employed by the first claimant since 30 June 2021. He resigned on 24 March 2025 and has been placed on 12 months’ paid garden leave until 24 March 2026. The first claimant is an entity which researches and develops quantitative trading strategies. It is part of the G-Research group. Its intellectual property has been assigned to, and is owned by, the second claimant, which is an affiliated company of G-Research, incorporated under the laws of the Marshall Islands. On Friday 21 March 2025, the defendant accepted a job offer from one of G-Research’s principal competitors, Citadel Securities LLC. He resigned from the first claimant on Monday 24 March 2025. In the period immediately following the defendant’s resignation, it became clear to the claimants that the defendant had copied and misused information which the claimants contend contains confidential information and trade secrets. The defendant accepts that the text files and photographs which he copied contain a substantial amount of confidential information; but he contends that it was nonetheless not of trade secret quality, and that some of the information was in the public domain and so not confidential at all.

These proceedings commenced on 26 March 2025. The claimants contend that the defendant: (i) breached his contractual obligations under his employment contract; (ii) breached his equitable duties of confidence to the claimants, and/or regulation 3 of the Trade Secrets Regulations; (iii) misused the claimants’ confidential information; (iv) breached the fiduciary duties he owed to the claimants in respect of confidential information; (v) infringed the copyright in the claimants’ copyright works, contrary to Section 17 of the Copyright Designs and Patents Act 1988; and (vi) was (amongst other things) unjustly enriched at the first claimant’s expense.

On 27 March 2025, the claimants obtained (without notice) an imaging orderand injunctions(from HHJ Hacon). On the return date (3 April 2025), and by consent, Richards J granted the claimants an inspection order, and continued the injunctive relief. Execution of these orders revealed (among other things) that: (i) over a three day period between Saturday 22 and Monday 24 March 2025, the day that he resigned (and when he should have been at work), the defendant took 1,087 photographs which contain the claimants’ confidential information (as displayed on his laptop screen which was logged in remotely to the first claimant’s IT systems) using a personal iPad that had been given to him as a welcome gift by Citadel Securities just days before; and (ii) over a period of months, dating back to at least 17 July 2024, the defendant had created, and frequently amended, several text files in markdown format which contain the claimants’ confidential information. Over 400 of the photographs relate to ‘Humber’, which the claimants allege is a highly valuable trading strategy, only recently developed by the first claimant following the expenditure of significant time and resources. In the text files, the defendant repeatedly recorded that he could (amongst other things) “replicate” Humber for a competitor. The meaning of this is contested between the parties.

The claimants seek to protect themselves against what they contend would be the irreparable harm they would suffer if the defendant were allowed to join a competitor equipped with their confidential information. They seek a final injunction, extending for two years beyond the defendant’s contractual period of garden leave, as well as financial and other remedies.

The defendant denies liability and the claim to injunctive relief. In essence, whilst he admits taking the photographs and making the text files, he contends that the two activities took place completely separately. He contends that the text files were made to assist him with interview preparation, and no part of their contents has been disseminated. He alleges that the photographs were part of an aide memoire, and that he acted impulsively in taking them. The photographs were also never disseminated. The defendant generally denies that he has caused, or could cause, the claimants substantial harm. He denies that the claimants are entitled to injunctive relief, contending that such relief would place the claimants in a better position than they would have been had the defendant not misused their information.

There is an agreed list of issues comprising (with various sub-issues): (i) the duties owed by the defendant to the claimants; (ii) the defendant’s alleged breaches of duty; (iii) the claimants’ entitlement to injunctive relief, its nature and extent; and (iv) the financial remedies to which the claimants are entitled. Amongst the sub-issues identified under the breaches of duty issue are: (v) whether some or all of the information defined in the Confidential Schedule to the particulars of claim as ‘Confidential Information’ is (a) confidential information, (b)of a trade secret quality, and (c)copyright material; and (vi) to what extent the defendant has, from 1 June 2024 onwards, engaged in unauthorised access to, appropriation, and/or copying of any documents, materials, information or electronic files containing confidential information and/or copyright material belonging to the claimants (and/or had been making preparations to do so).

In light of the order for an expedited trial, the parties no longer invite the court to order costs budgeting. That left only two areas to be addressed at the case management hearing on 18 September. The first was the resolution of outstanding issues in relation to disclosure. These had been considerably narrowed as a result of a constructive dialogue between the parties’ legal representatives shortly before the hearing. This meant that only three issues for disclosure remained outstanding at the start of the hearing. One of these (issue 6) was resolved following oral submissions, and after some suggestions from the court, during a short, further adjournment early after the court resumed following the luncheon adjournment. On this aspect of the case, it was Mr Ciumei KC who addressed the court for the claimants (although Mr Craig KC’s later submissions have some relevance to the first of these outstanding disclosure issues).

The second outstanding issue was the defendant’s application, dated the previous Friday, 12 September, seeking permission to adduce expert evidence on quantitative investment and trading strategy development from Mr Colin Knight, and any consequential directions. This application is supported by the witness statement of the defendant’s solicitor, Mr Nabeel Sheikh, also dated 12 September. It was Mr Craig KC who addressed me for the claimants in opposition to this application.

Since starting to prepare this written judgment, there have been several further developments. On Monday 22 September, the claimants filed an updated composite draft of the parties’ Disclosure Review Document, reflecting positions agreed between the parties at the hearing. I had indicated that I would set aside the whole of Wednesday 24 September to start work on this judgment. On Tuesday 23 September, however, I received a letter from the claimants’ solicitors, A & O Shearman, which had been written the previous evening and copied to the defendant’s legal team. This informed me that there remained a dispute between the parties with respect to: (i) the defendant’s proposed disclosure issue 4; (ii) the defendant’s proposed disclosure issue 8; and (iii) the data sources/locations to be searched in respect of the defendant’s disclosure, as set out in the answer to question 2 of the defendant’s section 2 questionnaire. This letter explained that the dispute in respect of issue 8 was different to that which had been set out in the parties’ respective written submissions (because its formulation had changed). The parties had not addressed the court orally on that, or on the defendant’s disclosure sources, at the hearing. Although the parties would continue to discuss matters in the hope that these could be resolved, or at least narrowed, I was invited to direct that, in the absence of agreement, the parties should have until 4pm on Friday 26 Septemberto make any further written submissions that they might wish to make on Issue 8 and the defendant’s disclosure sources.

As regards expert evidence, the claimants anticipated that the court would give its judgment on whether expert evidence was necessary, in principle, at the same time as its determination on disclosure. If the defendant’s application for expert evidence were to be dismissed, then clearly no further steps would be necessary. If, however, the application were to be allowed in respect of any of the five matters advanced in the defendant’s application, the claimants proposed that the parties should be given an opportunity to discuss the implications between themselves, and, if necessary, for the court to list a short further hearing.

In response, I directed that, in the absence of agreement, the parties should have until 3pm on Friday 26 September to make and file any further written submissions they might wish to make on issue 8 and the defendant’s disclosure sources. That was so that, hopefully, those submissions would reach me before the weekend. I indicated, however, that the parties must appreciate that this would, inevitably, delay the production of my judgment.

Shortly before lunch on Friday 26 September, I received a forwarded email from the claimants’ solicitors (copied to the defendant’s legal team). This acknowledged that the current deadline for written submissions to address outstanding issues relating to the disclosure review document following the hearing held on 18 September 2025 was 3pm that afternoon. The email informed the court that the parties were continuing to discuss the disclosure issues, as previously directed, to see if the parties could reach agreement. By agreement between the parties, I was asked to extend the deadline for written submissions “briefly” until 3pm on Monday 29 September 2025, as those discussions were continuing. In the meantime, I was invited not to make any judgment until receipt of those written submissions. I directed Chancery Judges Listing to respond to this letter, pointing out that I had set aside Monday 29 September for further work on my judgment. If the parties were to delay until 3.00 pm on that day, I could not predict when any judgment might be forthcoming. At about the same time as they acknowledged my directions, Chancery Judges’ Listing relayed to me a request from the clerk to the claimants’ leading counsel inquiring after my availability over the next couple of weeks for a half day’s hearing, either remotely or in person. I was told that the parties had not dealt with all the issues at the previous week's hearing, and that a further hearing might be required if they were not able to resolve the outstanding matters. I did not respond to this inquiry since I considered it to be premature pending the handing down of this judgment, not least because of the impossibility, until then, of identifying the extent of any matters remaining in dispute between the parties, and thus estimating the length of any hearing.

On Friday 26 September, both parties filed and served further written submissions, although the claimants’ submissions were not filed until shortly after 9.00 pm and they did not reach me until (unprompted) I accessed the unprocessed filings section of the CE-File on the morning of Monday 29 September. For the defendant, Ms Goodman’s submissions extend to ten pages. They cover the existing disclosure issue 4 (on which I had already received written and oral submissions) and the newly further re-formulated issue 8, together with ancillary disclosure issues (notably custodians and date ranges, and the manner and intensity of the review of document repositories/management systems, communication channels, devices and digital accounts). More than half of Ms Goodman’s written submissions are directed to her application to adduce expert evidence, including submissions on the propriety and proportionality of the instruction of a single joint expert, and the five issues on which any expert should be asked to opine.

Ms Goodman’s written submissions are the subject of extended criticism from the claimants’ solicitors in an email to the court timed at 20.41 on 26 September. This reads as follows:

The claimants’ further written submissions extend to six pages in total. They address the matters relating to the draft disclosure review document that were not dealt with in oral submissions at the hearing on 18 September 2025 “as directed”. They also explain why the claimants do not consider it to be appropriate to address issues relating to expert evidence by way of written submissions. That is because the court’s direction plainly did not permit the parties to file written submissions in relation to expert evidence. Further, as explained in the letter to the court from the claimants’ solicitors on 22 September 2025, the claimants anticipate that the court will give its judgment on whether expert evidence is reasonably required in principle, in light of the submissions made at the hearing on 18 September 2025. If (contrary to the claimants’ position) the court were to determine that expert evidence is reasonably required, a number of consequential matters would arise, including (among other things): (i) the relevant field(s) of expertise; (ii) the precise formulation of the issue(s) for expert evidence; (iii) whether there should be a single joint expert or separate experts for each side; (iv) the timetable for expert evidence; and (v) any potential reservation of the parties’ positions as to the admissibility, relevance and appropriateness of such expert evidence. These are significant matters that were not addressed at the hearing on 18 September 2025. Accordingly, and as set out in the claimants’ 22 September 2025 letter to the court, the claimants submit that those matters cannot properly be resolved at this stage. Instead, the claimants suggest that, if the court were to make an order that expert evidence is reasonably required in principle, the should parties be given the opportunity to discuss the implications between themselves, and, if necessary, to apply to the court to list a further short hearing to resolve any matters that cannot be agreed.

At the risk of being thought facetious, the notion that any ‘short hearing’ might be capable of resolving any matters remaining in dispute in this fiercely contested litigation seems to me to be overly optimistic. In this connection, I note the early observation of Mr Ciumei KC at the recent hearing (recorded at pages 5-6 of the transcript) in which he endorsed my comment at the earlier hearing that nothing in this case has been easy to resolve thus far.

In oral submissions I was taken to the judgments of Sir Geoffrey Vos C in McParland & Partners Ltd v Whitehead [2020] EWHC 298 (Ch), [2020] Bus LR 699 at paragraphs 2-4, 7-9, 35, 43-48, 51, and 56-7; of Bryan J in Lombard North Central Plc v Airbus Helicopters SAS [2020] EWHC 3819 (Comm) at paragraphs 24 and 30; and of Deputy Master Francis in Performing Right Society Ltd v Qatar Airways Group QCSC [2021] EWHC 869 (Ch) at paragraph 33. From these authorities, I derive the following propositions which are of relevance to the present case:

Issues for disclosure are very different from issues for trial. The issues for disclosure need not be numerous. They do not need to be detailed or complicated, particularly in a relatively straightforward dispute. They will almost never be legal issues; and they will not include factual issues that are already capable of being fairly resolved from the documents available on initial disclosure.

The identification of issues for disclosure is quite a different exercise from the creation of a list of issues for determination at trial. The issues for disclosure are those which require extended disclosure of documents (i.e. further disclosure beyond what has already been provided on initial disclosure) to enable them to be fairly and proportionately tried. The parties need to start by considering what categories of documents, likely to be in the parties' possession, are relevant to the contested issues before the court.

Unduly granular or complex lists of issues for disclosure are to be avoided. Likewise, the models chosen should simplify the process rather than complicate it. Model C may be appropriate for an issue where vast documentation is likely to exist, most of which is irrelevant to the actual dispute. Model D may be appropriate to the central issues in the case, and where there is significant mistrust between the parties. No extended disclosure at all may be required for other issues.

It is not simply where the parties mistrust each other that Model D may be appropriate, but also where it is a central issue in the case: essentially, the central nub of the dispute.

The absence of any pleaded reply on the part of a claimant is no real indicator of the true extent of the factual disputes in issue between the parties.

Three further important propositions are, I think, also implicit, even if they are not expressly articulated, in McParland, as follows:

Multiple, and overlapping, issues for disclosure should be avoided wherever possible.

The focus should be on the disclosure of the relevant documentation, rather than the precise formulation of each issue for disclosure. The overall effect of the disclosure issues should be at the forefront of the exercise.

The crucial inquiry must always be whether the disclosure issues, when rigorously applied, will produce the documents that will enable the factual issues in dispute to be fairly and proportionately tried. The principled application of PD 57AD requires litigators to step back and ask: What are the real issues in dispute between the parties which need to be decided by reference to the documents?

I must also bear in mind the requirements of Practice Direction 57AD (governing disclosure in the Business and Property Courts); and, in particular, paragraphs 6.3 and 6.4. The former limits the court’s power to make an order for extended disclosure that is search-based (i.e. Models C, D and/or E) to cases “where it is persuaded that it is appropriate to do so in order fairly to resolve one or more of the issues for disclosure”. Paragraph 6.4 provides that:

I agree with Mr Ciumei KC that when approaching all of the disclosure issues in this case, it is important to bear in mind (as I do) three background issues. These are: (1) the nature of the dispute; (2) the proper approach to be taken to deciding on the issues for, and the scope of, disclosure; and (3) the timetable leading up to, and the further time available before, the trial. Paragraph 9 of my directions order provides for search-based extended disclosure to be given by 4:30 pm on 22 October 2025. I must also bear issues of proportionality firmly in mind. However, these considerations must all be weighed in the balance against the need to ensure, so far as is practicable, that the parties are on an equal footing, and can participate fully in the proceedings, with the parties and their witnesses being able to give their best evidence.

The defendant has identified the following as disclosure issue 4:The trading strategy ‘stage’ which each item of the GR Information related to. He says that the claimants should give narrow, search-based disclosure in accordance with Model D. Essentially, Ms Goodman submits thatthe matters pleaded at paragraph 17 of the particulars of claim (and developed further later in that statement of case) are central to the claimants’ case. In particular, that case is predicated on the defendant having had access to “highly confidential financial researchand modelling in the development of trading strategies”, and the “exclusivity of the research and strategies.” If he did not have that access: (1) he cannot have copied material of any particular value to the claimants or their competitors; and (2) he would not be able to ‘replicate’ any valuable trading strategies (which would impact on the injunctive relief to which the claimants would be entitled). Ms Goodman points out that the defendant positively avers that he only had access to the early stages of the development of trading strategies (whether that be ‘stage’ in the general sense, or a ‘stage’ specifically labelled as such by the claimants). The claimants response is to say that there were no formal ‘stages’ in the development process; but the defendant asserts, based upon his experience as an employee of the first claimant, that there was a certain juncture (or stage) at which he was cut off from the development of a trading strategy: the point at which the trading strategy proper was developed. In any event, Ms Goodman emphasises that the claimants cannot simply assert that this is not an issue because they do not recognise any staging: they have not sought any summary determination on this issue, and it accordingly remains live unless the claimants concede the point. Ms Goodman says that the defendant’s lack of access to the valuable later stages of the trading strategy development process is a ‘central issue’ in the case (citing Lombard North Central). Model D disclosure is therefore appropriate.

The claimants object to the inclusion of this issue and say that it should not be an issue for disclosure at all; but if it is, disclosure should be limited in accordance with Model C (disclosure of particular documents or narrow classes of documents). The ‘Development Stages’ described by the defendant at paragraph 20 of his defence is said to be a framework of his own creation, and it is not understood, or agreed to, by the claimants. It is irrelevant. It is no part of the claimants’ case that the confidential information related to a particular ‘development stage’. Attempting to carry out any kind of disclosure search on such a foundation will inevitably lead to confusion and further dispute, which cannot be accommodated in the current timetable. Issue 4 should therefore be omitted.

Ms Goodman expands upon her earlier submissions in her later document. Whilst I did not direct, or allow, further submissions on this issue, it is only fair that I should have regard to them, despite the claimants’ invitation not to do so. It is the defendant who seeks to invite the court to treat this as an issue for disclosure. It is he who bears the burden on this issue. Ignoring Ms Goodman’s further submissions might only lead to an application for permission to appeal if I were to refuse to identify issue 4 as an issue for disclosure, diverting time and resources away from preparations for an expedited trial.

Ms Goodman reminds the court that at the hearing, she submitted that, regardless of whether the claimants agree that the development of a trading strategy had formal ‘stage’ structures (with the labels applied to them by the defendant at paragraph 20 of his defence), as a matter of logic that must be the case. Indeed, the defendant submits that it is an obvious corollary of the ‘comprehensive information security regime’ (which the claimants plead at paragraph 17 of the particulars of claim) that, as a project progresses from the early upstream/raw data stage to something approximating a valuable trading strategy, more stringent security arrangements would have applied (and, in particular, the level of access that employees of the first claimant would have had to the research project/trading strategy in development). In the words of Mr Ferguson (at paragraph 15 of his first affidavit):

The claimants therefore attest, in their own words, to differing "levels of information", with differing applicable security arrangements. The defendant expects to see communications discussing what stage, or juncture, in the trading strategy development process had been reached with respect to the GR Information. The defendant's proposed issue 4 asks for disclosure with respect to ‘stages’ (as a concept), rather than disclosure by reference to the development stages as pleaded at paragraph 20 of the defence. Accordingly the claimants' objections are misplaced: if they consider that the term ‘stages’ was not used by them, it is open to them to suggest alternative wording to explain how they structured the development of a trading strategy. The parties will, moreover, be best placed to propose and refine keyword searches, with words such as ‘level’ (used by Mr Ferguson, as quoted above), ‘process’, ‘development’, ‘phase’, or ‘juncture’, which can all capture communications which demonstrate internal delineation of parts of the trading strategy development process.

I bear firmly in mind Ms Goodman’s submission that the defendant's contention is that he only ever had access to ‘upstream’, low-value information because he was a mere data scientist. To the extent that he boasted to third parties that he had a view of the claimants’ entire trading strategy, or that he could have ‘replicated’ Humber for the benefit of a competitor, he simply could not have done so. In other words, this was mere ‘puff’ (as I sought to characterise it) or ‘hot air’ (as Ms Goodman preferred to describe it). Ms Goodman accepts that this has no bearing on the confidential quality of the information. Rather, it is relevant to the issue of damages and relief, both generally and, in particular as to the temporal and other extent of any injunctive relief.

However, I also bear in mind that the parties have now agreed disclosure issue 6, whereby the claimants are to give disclosure (in accordance with Model C: disclosure of particular documents or narrow classes of documents) of:

It is also relevant that the defendant now seeks disclosure in accordance with the re-formulated issue 8. This reads:

I turn then to the recently re-formulated disclosure issue 8, on which the defendant seeks disclosure in accordance with Model D. This condenses the defendant's previous formulation. It is said by Ms Goodman to be targeted at a factual issue raised by the pleadings. A key part of the defence, since it relates to Humber, is that the defendant was only involved with Humber at an early stage, having been cut off from the trading strategy (save for upstream data processing) at the start of January 2025. In particular, if other teams made material contributions to Humber, such that the trading strategy that was ultimately deployed was materially distinct from the last version on which the defendant worked, the defendant’s knowledge of Humber will be (commensurately) less valuable, and his ability to ‘replicate’ Humber will be non-existent or, at least, decreased. If the defendant is right, the claimants’ case will be critically undermined in circumstances where:

To the claimants’ knowledge, the defendant could not have replicated Humber elsewhere. Accordingly, the claimants’ case with respect to any Springboard relief (insofar as it is based on the possibility of the defendant replicating Humber elsewhere) will be weakened still further; and

Any commercial value of the GR Information relating to Humber will be insignificant, with a consequent impact on any relevant financial relief.

In summary, the defendant's position is that the claimants are not entitled to injunctive relief of the nature, or the length, sought, in circumstances where the defendant did not have access to (or, indeed, security clearance to access) downstream ‘alpha’ code. The reformulated issue 8 looks specifically at how Humber itself was developed. If work on Humber was largely undertaken by teams which excluded the defendant (as he alleges), then whatever material relating to Humber he may have had within his possession will have been largely valueless, because it would have been early stage, upstream, code, which bears no resemblance to Humber as it was actually developed or deployed. The defendant is confident that documentary evidence of the nature sought by the newly reformulated issue 8 will be available.

The new issue 8 is said to be central to the defendant's case. He does not deny having misappropriated GR Information. The central issue for the court at trial will therefore be to identify the relief to which the claimants are entitled. The defendant's position is that they will be entitled to minimal relief, in circumstances where, put simply, he poses no (or only minimal) danger to the claimants' business. If he could never have posed any danger to the claimants' business (even prior to the deletion of the GR Information from his accounts and devices), then that submission will have great force behind it. It also has a bearing on his outstanding discharge application, and the propriety and proportionality of all the steps the claimants have taken thus far in the litigation. Being ‘central’ to the dispute, it is appropriate that the claimants should be ordered to provide disclosure on the model D basis (again citing Lombard North Central).

The claimants object to the inclusion of this issue (as originally formulated) because they say that it has no bearing on the dispute whatsoever. It is precisely the type of wild goose chase that will obscure the real issues in the case, and place an unnecessary burden on the parties (and the court), with the attendant danger of disruptive satellite disputation. The proposed issue has no relevance to any of the factual issues in dispute. The defendant is said to relies upon paragraph 21 of his defence (at section 1A to his disclosure review document). This passage is said to disclose no dispute of fact which could found a proper or appropriate issue for disclosure. Accordingly, the claimants say that the court should not include this issue in the approved disclosure review document.

I note that paragraph 21 of the defence (read in conjunction with paragraph 20) pleads a tabular ‘linear approximation’ of the tiers applied in the development process of trading strategies “that was, in practice, disjointed”. It pleads, in vague, generic terms, that the output of the defendant’s data science team (and the defendant’s own contributions) was often diluted by, or substituted in favour of, contributions made by other data science teams. Where this happened, the end product of the early stages was unknown to the defendant. Moreover, it is pleaded that it was not uncommon for quantitative researchers to merge research projects relating to one potential trading strategy into the development process of another (without reference to the data scientists), thereby limiting the defendant’s knowledge and understanding of the characteristics of a given trading strategy (even at the early stages).

The claimants expand upon their submissions (in relation to the original formulation of issue 8) in the document they filed last Friday. They submit that issue 8 is not a proper issue for disclosure for the following reasons:

First, at its core, the claimants’ case is simple: the defendant knows the essential details of the extremely confidential and valuable trading strategy known as ‘Humber’ and, unless the court intervenes, he will use that information to help a competitor to replicate Humber, or there is a grave risk of this. The claimants remind the court of the submissions of Mr Craig KC at pages 144-150 of the transcript of the 18 September 2025 hearing; the evidence at paragraph 42 of the defendant’s 2^nd witness statement;the commentary upon that evidence at paragraph30 (a) of Mr Sinclair’s 5^th witness statement; and the defendant’s own repeated assertions, in contemporaneous, documents that he could (and would) ‘replicate’ Humber (as reproduced at paragraph 5 of the claimants’ skeleton argument for the 18 September hearing).

The idea or rationale behind a trading strategy is said to be of crucial importance. So, even if it is the case that the defendant did not steal (and is unaware of) all of the details of how Humber is implemented, that does not alter the fact that what the defendant did have access to (whether such access was authorised or not), and what he did steal, would allow a competitor to replicate Humber in its essential parts. Consequently, that information is of enormous value, and any further misuse or unauthorised disclosure thereof threatens to cause huge damage to the claimants.

Further, as was conceded by the defendant’s counsel in oral submissions, the defendant stole valuable confidential information: see page 133 of the transcript, line 18. Further still, it was also conceded by the defendant that the question of whether information is valuable is simply not a necessary element of whether it is confidential: see page 31 of the transcript, lines 13-20. It may be the case that the issue of the value to be placed upon the confidential information is relevant to the assessment of damages for breach of confidence, or as to the suitability of a remedy, such as the injunction sought by the claimants to prevent the defendant working for a period for a competitor. However, there is no doubt that the information which the defendant stole is valuable. The value of Humber as a trading strategy is significant, as the defendant himself well knows (as evidenced by the figure the defendant himself set out in the confidential schedule to the particulars of claim). Further, it is obvious that the information is highly confidential because: (i) the defendant stole it, and in doing so went to considerable effort to evade the claimants’ security measures; (ii) the claimants have gone to great lengths and expense to protect it; and (iii) there is no evidence that any of the parties are not rational actors.

It follows that disclosure evidencing ‘material contributions’ (or, presumably, work undertaken) to Humber is simply irrelevant to the issues in dispute. The defendant knows the strategy, irrespective of the extent to which he was involved in creating each component part of it. Accordingly, any documents responsive to the proposed issue 8 would have no probative value one way or the other. That is no doubt why the agreed list of issues for trial makes no reference to ‘contributions’ (or ‘work undertaken’) to Humber, or to the ‘incorporation’ of other research into Humber.

Second, the defendant appears to contend that the disclosure of issue 8 documents is necessary because they go to the value of the relevant confidential information. This is not a centrally relevant issue. It is in any event hardly a question that is in any real doubt. Further, it is not a sound basis for including issue 8 in the disclosure review document for two reasons: (i) The fact that other people may know other information about Humber is logically irrelevant to the value of the information that the defendant knows and/or stole. It is the absolute value of the information that the defendant knows that is relevant; not its relative value as compared to other categories of information known by others. (ii) In any event, the parties have already agreed the scope of disclosure to be given in respect of value pursuant to agreed issue 6, and the specific categories of documents listed in rows 8-10 of section 1B of the disclosure review document. Accordingly, the inclusion of proposed issue 8 (or indeed issue 4) to also deal with value would be duplicative, unduly granular and complex, and contrary to the clear guidance given by Sir Geoffrey Vos C in McParland (at paragraphs 47 and 56-57).

Third, it is far from clear what searches the claimants would be expected to undertake in respect of, and what documents might exist that are responsive to, the proposed issue 8. The claimants have already agreed to give disclosure of messages from the Humber Slack Channel (i.e. the internal communications system predominantly used by the claimants) that are relevant to value. It is unclear what else the defendant is looking for. The defendant’s formulation is broad and vague; and he appears to have made no attempt to comply with the principle that the parties should start by considering what documents are actually likely to exist before formulating issues for disclosure: see McParland at paragraph 46 (explaining that the issues for disclosure are “only those key issues in dispute, which the parties consider will need to be determined by the court with reference to contemporaneous documents in order for there to be a fair resolution of the proceedings”) and paragraph 56 (emphasising that “The parties need to start by considering what categories of documents likely to be in the parties’ possession are relevant to the contested issues before the court.”). Issue 8 is precisely the type of wild goose chase that the disclosure regime under PD 57AD is intended to avoid. It will obscure the real issues, and make disclosure unnecessarily time-consuming and burdensome (potentially for both parties), particularly in the context of an expedited timetable to trial.

Fourth, the court is invited to note that the defendant seeks disclosure (particularly by subparagraph (3) of the originally formulated issue 8) of documents concerning research that he was not privy to during the course of his employment. In other words, he seeks, through these proceedings, to obtain yet further confidential information belonging to the claimants, beyond that which he already knows, or has previously managed to steal. That is of real concern to the claimants in light of the defendant’s admitted theft of, and propensity to misuse, such information. In that context, the court is invited to approach the defendant’s disclosure requests with an appropriate degree of caution. Given that the information sought is at very best of peripheral relevance to the actual dispute, the risk of the defendant misusing the information obtained through disclosure is a further factor that should militate against the inclusion of proposed issue 8.

In the email which accompanied their most recent filed submissions, the claimants say that the revised formulation of issue 8 suffers from all the same problems as the original formulation. What matters is the confidentiality, and value, of the information stolen by the defendant; the ‘work on Humber’ undertaken by others has no bearing on the issues in the case. Accordingly, the claimants invite the court to reject this new version of issue 8 for the same reasons they set out in their accompanying written submissions.

In my judgment, the claimants overstate the position when they assert that, on the defendant’s own evidence, it would be possible for a competitor who is told the essence of the trading strategy to engineer their own code to implement it. At paragraph 42 of his 2^nd witness statement, the defendant concludes:

Subject to these qualifications, however, I accept the claimants’ submissions. In my judgment, it is necessary to step back and look at the reformulated disclosure issue 8 in the context of the claim, and the defence, as a whole. It seeks extended disclosure of: Work on Humber undertaken by, or originating from, teams which excluded the defendant. It is expressly directed to looking specifically at how Humber itself was developed. It is premised on the proposition that if the work on Humber was largely undertaken by teams which excluded the defendant (as he alleges), then whatever material relating to Humber he may have had within his possession will have been largely valueless, being early stage, upstream, code, which bore no resemblance to Humber as it was actually developed or deployed. However, the true focus of this litigation must be on the confidential material that the defendant admits that he accessed, and misappropriated, from the claimants. Ms Goodman says that the claimants will be entitled to minimal relief in circumstances where the defendant poses no (or minimal) danger to the claimants' business. But the extent of the risk that the defendant poses to that business will be a matter to be evaluated by the trial judge on all the evidence presented to the court. If that evidence includes the products of disclosure issue 6, the judge will have the documentary material relevant to “the commercial and/or negotiating value of both (i) deployed; and (ii) non-deployed trading strategies within the confidential and/or copyright material captured by the GR Information”. I fail to see what further material documentation will be disclosed by searches directed to ‘Work on Humber undertaken by, or originating from, teams which excluded the Defendant’. Such disclosure would be superfluous to any reasonable, or proportionate, requirement. In short, disclosure of documentation relating to the work on Humber is irrelevant to the fair resolution of this litigation. Since the disclosure would relate to work undertaken by teams excluding the defendant, it would also afford the defendant access to further confidential material. Given the defendant’s previous, acknowledged misappropriation of the claimants’ confidential information, and the (at best) peripheral relevance of the material sought to the actual dispute, I accept that the risk of the defendant misusing the information obtained through disclosure is a further factor that should militate against the inclusion of the reformulated issue 8 on the grounds of proportionality.

Had I taken a different view, and ordered disclosure in accordance with either issue 4 or the reformulated issue 8, I would have ordered model C disclosure as against the claimants. I would not have accepted that disclosure on either of these issues was central to this litigation. Further, the parties have agreed model C disclosure for the claimants in relation to issue 6; and I see no reason why any different disclosure model should apply to either of issues 4 or 8. I therefore refuse to direct disclosure issue 8.

I turn to ancillary disclosure issues, concerning the data sources and locations to be searched in respect of the defendant’s disclosure. I understand that the defendant is content to agree to undertake a review of his digital devices and online storage accounts as provided for in the disclosure review document. Had he not been, I would have ordered him to do so. I would have rejected any submission that none of his devices or online storage accounts needed to be searched for material relevant to the issues for disclosure on the basis that they have already been searched in connection with the process under the imaging and inspection order, for the reason set out at paragraph 13 of the claimants’ further written submissions.

As for email messages contained on accounts created following the commencement of the litigation, the claimants have pointed to the defendant's continuing obligation to disclose known adverse documents. The defendant points out that he is also under an obligation (under para 3.1 (6) of PD 57AD) to "use reasonable efforts to avoid providing documents to another party that have no relevance to the issues for disclosure in the proceedings. Ms Goodman says that it is with a keen eye to this latter duty that the defendant proposes not to search any accounts created after the commencement of this litigation, in circumstances where these proceedings began with the removal and imaging of all 14 of his devices. She emphasises that there is simply no suggestion or extant allegation that, following the commencement of the litigation, the defendant has misappropriated any more of the claimants' confidential information. The claimants' security systems are (on their own case) highly advanced and complex, and would no doubt have detected any attempt by the defendant to further access the claimants' information. To the extent that the defendant has discussed any confidential information after this litigation commenced, those discussions were with his legal advisors, with a view to obtaining advice (and are accordingly subject to litigation privilege). Whilst the claimants are correct to suggest that, if a review were to be undertaken, the defendant would be entitled to assert privilege (where appropriate), the defendant is certain that the sole outcome of reviewing devices and accounts post-dating the commencement of the litigation will be an undue, and unnecessary, increase in the overall costs of the disclosure exercise, as it will only produce privileged communications between the claimants and the defendant.

The claimants submit that there is no basis for the proposed exclusion from disclosure of all email messages contained on “accounts created following commencement of this litigation”. Obviously the claimants do not expect privileged material to be disclosed. However, it is entirely possible that such accounts contain relevant emails that are not privileged, and which contain evidence pertaining to the defendant’s misuse of the claimants’ confidential information before, or after, the commencement of these proceedings. It is said to be noteworthy that the defendant has sought to rely on a previous order of Arnold J in other litigation in support of his application for expert evidence. Yet that order also dealt with disclosure in those proceedings, and ordered disclosure of documents coming into existence after the alleged dates of misuse, but which related to that earlier misuse. There is, in any event, a continuing duty of disclosure. Accordingly, the disclosure review document should require such accounts to be searched, and for any non-privileged, disclosable documents identified by such searches to be disclosed in the usual way.

I accept the claimants’ submissions and direct that the disclosure review document should require all the defendant’s email accounts to be searched, and for any non-privileged, disclosable documents identified by such searches to be disclosed in the usual way. There is a continuing duty of disclosure. Any communications evidencing post-litigation misuse of the claimants’ confidential information is properly disclosable. If there is no such disclosure to give (as the defendant contends), then this may assist the defendant’s own case as to the extent of the relief to be afforded to the claimants at trial.

On the admission of expert evidence, I was taken to CPR 35.1 and 35.4. I was also taken to the following authorities: Barings Plc v Coopers & Lybrand [2001] PNLR 379 at paragraph 45 per Evans-Lombe J; Clifford v Chief Constable of the Hertfordshire Constabulary [2008] EWHC 2549 (QB) at paragraphs 26 and 31 per Wynn Williams J; British Airways Plc v Spencer [2015] EWHC 2477 (Ch) at paragraph 63, 68 and 69 per Warren J; The RBS Rights Issue Litigation [2015] EWHC 3433 (Ch) at paragraph 18 per Hildyard J; Astex Therapeutics Ltd v AstraZeneca AB [2017] EWHC 1442 (Ch) at paragraph 42 per Arnold J; Bridgewater Associates LP v Minicone 16 July 2020 (Employment Arbitration Tribunal); AlphaSharp Ltd v ADG Capital Management LLP [2021] EWHC 1779 (Comm) at paragraph 38 per Waksman J: and Henderson & Jones Ltd v Salica Investments Ltd [2025] EWHC 475 (Comm) at paragraphs 235-6 per Calver J.

From these authorities, I derive the following propositions:

Expert evidence is admissible in any case where the court accepts that there exists a recognised expertise governed by recognised standards and rules of conduct capable of influencing the court’s decision on any of the issues which it has to decide; and the witness to be called satisfies the court that he has a sufficient familiarity with and knowledge of the expertise in question to render his opinion potentially of value in resolving any of those issues.

Evidence which meets this test can still be excluded if the court takes the view that calling it will not be helpful to the court in resolving any issue in the case justly. Such evidence will not be helpful where the issue to be decided is one of law, or is otherwise one on which the court is able to come to a fully informed decision without hearing such evidence.

Expert evidence cannot assist in resolving a pure issue of disputed fact. This falls to be determined on the factual evidence. This may be subject to a qualification that I tentatively identify in the following paragraph of this judgment.

The burden of establishing that expert evidence is both (i) admissible and (ii) reasonably required (in the sense that it is not just ‘potentially useful’) is on the party which seeks permission to adduce the evidence concerned.

The first matter to consider is whether, looking at each pleaded issue, it is necessary for there to be expert evidence before that issue can be resolved. Expert evidence will be necessary, rather than merely helpful, if the court would not be able to determine the issue without it. In that situation, the expert evidence must be admitted.

If the expert evidence is not necessary, because the court would be able to determine the issue without it, the second matter for the court to consider is whether it would be of assistance to the court in resolving that issue. If it would not even be of assistance to the court, it should refuse permission to admit expert evidence.

If the expert evidence is not necessary, but would be of assistance to the court in resolving the issue, the court must proceed to consider the third matter, which is whether, in the context of the proceedings as a whole, expert evidence on that issue is reasonably required to resolve the proceedings. In such a case, the court has to strike a balance, and assess the proportionality of its admission. In striking that balance, the court should be prepared to take into account a series of disparate factors, including the value of the claim, the effect of a judgment either way on the parties, who is to pay for the commissioning of the evidence on each side, and the delay, if any, which the production of such evidence would entail (particularly delay which might result in the vacation of a trial date).

Complications may arise where a particular piece of expert evidence may go to more than one pleaded issue, or evidence necessary for one issue may need only slight expansion to cover another issue where it would be of assistance, but not necessary.

If evidence is not reasonably required for resolving any particular issue, it is difficult to see how it could ever be reasonably required for resolving the proceedings as a whole.

Before any experts are instructed, clear identification of the issues which they are going to be asked to address is required. Only if the issues are clearly identified is it possible to ascertain whether the experts can give evidence directed to those issues which is (i) admissible and (ii) likely to be of sufficient weight for the cost of preparing their evidence to be proportionate to what is at stake.

Although such matters were not ventilated before me in submissions, and any views I venture to express on this topic are therefore tentative, the particular circumstances of this case lead me to consider that there may be two further relevant considerations. First, whilst proposition (3) states that expert evidence cannot assist in resolving a pure issue of disputed fact (which will fall to be determined on the factual evidence adduced at trial), in cases concerning confidential information, or trade secrets, confidentiality restrictions imposed during the course of the litigation to protect the claimant’s interests in such property may prevent, or impede, the assembly and deployment of factual evidence relating to the commercial utility, and thus the value, of that property. In such circumstances, the evidence of an expert who has been given access to such information or secrets may be necessary, or of assistance, to the trial judge in resolving related issues of disputed fact, such as the extent to which they might be of assistance to a competitor of the claimant. That is because restraints upon the disclosure of such information to potential witnesses may inhibit, or prevent, the ability of the defendant to assemble and deploy such factual evidence. How can a defendant secure the factual evidence of competitors concerning the utility and value of the claimant’s information if he is prevented from disclosing it to such potential witnesses of fact? Secondly, a claimant who bears the burden of proof in the litigation, may, as a result, have a greater need of expert evidence than the defendant, who may be able to rely upon the lack of any potentially relevant expert evidence in support of a submission that the burden of proof has not been discharged. If expert evidence is reasonably required to enable the claimant to prove an issue at trial, and no such evidence is adduced, then the claimant is likely to fail on that issue. If expert evidence would merely assist in resolving an issue, however, then the burden of proof may have less of a part to play in the court’s decision whether or not to admit expert evidence. To this extent, a party which bears the burden of proof may face a lesser hurdle than the counter-party when it seeks to persuade the court to permit expert to be given at trial.

In the course of his oral submissions, Mr Craig KC took me to observations of Hildyard J in CF Partners (UK) LLP v Barclays Bank Plc [2014] EWHC 3049 (Ch) at paragraphs 123-4 for the proposition that one does not need to establish financial value for the purpose of a claim for breach of confidence or of copyright. Information can have commercial value because it is secret. There is inherent value, effectively, in the secrecy, and the inaccessibility, of confidential information. The relevant paragraphs of the judgment read:

Ms Goodman referred the court to a number of authorities in support of her expert evidence application. The first is the New York Employment Arbitration Tribunal case of Bridgewater Associates, LP v Minicone, decided on 16 July 2020. This was a case in which the claimant was a hedge fund, and the respondents were former employees. Amongst other complaints, the claimant alleged that the respondents had misappropriated trade secrets and used and disclosed confidential information in breach of their contractual obligations. Both parties’ experts gave evidence concerning a unique ‘Bridgewater logic’ or ‘Bridgewater approach’, which was described as ‘a well-known and widely used process in economics and other disciplines” (p. 8). The respondents’ case was that they had not used that Bridgewater logic in their later work, relying instead on “academic articles and books”; and their expert testified that the respondents’ “models and spreadsheets appeared to be based on academic literature and copied publicly available information, thus corroborating [the] testimony” of one of the respondents (p. 10).

At p. 10 of the award, the arbitral tribunal discussed the evidence provided by the respondents’ experts:

Ms Goodman points out that the English and Welsh courts have also recognised the utility of expert evidence specifically with respect to quantitative trading. In AlphaSharp Ltd v ADG Capital Management LLP [2021] EWHC 1779 (Comm), the court was concerned with a summary judgment application. The claim concerned licences granted by the claimant to the defendant. The claimant had developed a quantitative trading strategy, and had licensed IP rights in that strategy. In dismissing the summary judgment application, Waksman J observed (at paragraph 38) that:

I derive no assistance from any of these authorities. They decide no point of law or general principle, and lay down no rule of practice. Indeed, they decide nothing at all. In my judgment, Mr Craig KC rightly found it difficult to understand how any of these authorities could assist the court at all. Bridgewater was a decision of the New York Employment Arbitration Tribunal. Rules of evidence in arbitration are very different. Generally, a party is entitled to adduce any evidence it chooses to. Indeed, the applicable rules in the Bridgewater case - the national rules for the resolution of employment disputes of the American Arbitration Association – state:

As with Ms Goodman’s recently received further submissions on disclosure, I consider that I should have regard to her further written submissions on the expert evidence, and for the same reasons.

In her initial written submissions, Ms Goodman explains that the defendant considers that this is a case in which expert evidence is plainly necessary. The reasons are set out in Mr Sheikh’s first witness statement, served in support of the expert evidence application. The defendant has proposed five ‘expert evidence issues’ as follows:

Stages in trading strategy development;

Public domain assessment;

Valuation of confidential information;

Retention of value; and

Practical utility of confidential information.

As a general submission, Ms Goodman says that the information copied by the defendant consists largely of algorithmic trading code. It is (self-evidently) necessary for an expert to assist the court (and the parties’ legal advisors) in understanding (1) the nature of algorithmic code; and (2) the value of any such code.

Broadly, Ms Goodman further submits that valuation evidence will be central to the defendant’s case as to: (i) his motivation in reproducing the GR Information; (ii) the nature of that GR Information (and whether or not it is a trade secret); and (iii) any financial relief to which the claimant may be entitled. Ms Goodman points out that Mr Sheikh’s witness statement refers to the relevant pleadings in annex A, cross-referenced against each of the expert evidence issues. She submits that, in respect of each issue, the claimant has made an averment as to which expert evidence will be necessary for its determination. The claimants’ resistance to expert evidence is said to be nonsensical, and inconsistent with their own case regarding the nature of their algorithmic trading strategies. Ms Goodman relies upon paragraph 24 of Mr Sheikh’s witness statement. This explains that:

The claimants have themselves relied on the expert report of Mr Winrow to analyse the coding data extracted from the defendant’s electronic devices, as evidenced by A & O Shearman’s letter of 5 September 2025, exhibited as NS1/4. I note that in this letter the claimants resist the admission of any expert evidence on the basis that this “is not necessary, reasonably required or proportionate and will simply drive up costs”. They also state that they had instructed Mr Winrow, a computer forensics expert, to review the images taken of the defendant’s devices and accounts and to provide a report on relevant activity on those devices and accounts. I note that the defendant is not seeking to adduce any corresponding expert evidence from a forensic computer expert concerning the defendant’s digital devices and accounts. The field of expertise, and the nature of the instructions to the expert, are entirely different. This point does not assist the defendant’s application.

It is a common feature of disputes of this nature to include expert evidence. Mr Sheikh refers to an order made by the Linden J on 17 November 2020 in litigation between Citadel Securities (Europe) Ltd and GSA Capital Partners LLP & Ors under claim no QB-2019-004486. It also appears that expert evidence was within the contemplation of the parties in a previous dispute in which the claimants were involved in 2013. Reference is made to an Order of Arnold J, dated 24 October 2013, in claim no HC11C04301. I note that directions for expert evidence are always case-specific. I agree with the claimants’ submission that the directions orders in these two cases afford no real assistance to this court.

It is the claimants who bear the burden of proof in this case, which concerns the nature, and value, of technical descriptions of algorithmic trading strategies and actual code. They are required to prove that the defendant reproduced highly sophisticated and ‘extremely valuable’ code, which the claimants spent years developing, and which is (they say) unique in the industry. The subject-matter of this dispute is highly technical. If anything, however, the fact that the burden of proof in this case rests on the claimants, and they are the party who are resisting the admission of expert evidence, would seem to me to tell against permitting expert evidence to be adduced at trial. If expert evidence is reasonably required to enable the claimants to establish their case, and such evidence is not forthcoming at trial, then the claim should fail.

To the extent that the court considers that expert evidence will not be necessary on any particular expert evidence issue, Ms Goodman submits, in the alternative, that expert evidence will be of assistance to the court, and reasonably required in the proceedings (for the reasons previously given).

Ms Goodman elaborated upon her original written submissions at the hearing. During the course of the hearing, I inquired of Ms Goodman (at page 90 of the transcript) whether there was a need for separate experts, or whether a single joint expert would be as effective, and more proportionate. Mr Craig KC noted my suggestion (at page 91) when he opened his submissions. As will appear, the defendant would be content with a single joint expert, although the claimants would not. I also inquired whether Ms Goodman’s oral indication that Mr Knight’s fees would come to some £50,000 included an element for VAT (given that the defendant is not registered for VAT purposes). Ms Goodman was unable to answer that question but said that she would make inquiries. So far as I can discern, no response has yet been communicated to the court.

Before addressing the five ‘expert evidence issues’ addressed in Mr Sheikh’s witness statement, the claimants point out that that the defendant has failed to comply with the requirements of CPR 35.4. These require a party who asserts that there should be expert evidence to: (i) provide an estimate of costs; and (ii) identify the issues which the expert evidence will be asked to address. The defendant has provided no estimate of costs. Nor has he identified the issues which the proposed expert evidence would address. Instead, he has set out a number of amorphous ‘topic headings’. Self-evidently, so the claimants say, that will prove to be a recipe for chaos, with the experts on each side addressing topics in a different way, and potentially answering different points. More importantly, it reflects the fact that the defendant is unable to articulate the actual issue(s) and question(s) which he says that expert evidence should address. Reference is made to Astex at paragraph 42. The claimants say that it is worthy of note that the defendant does not suggest that his proposed ‘expert’ considers that these are expert issues, nor that they have been formulated in a manner that the ‘expert’ could properly consider.

The claimants address each of the five topic headings identified at paragraph 21 of Mr Sheikh’s supporting witness statement in their written skeleton argument prepared for the hearing. Mr Craig KC expanded upon these points in his oral submissions. Taking each heading in turn:

Stage in trading strategy development – identifying which stage in the trading strategy development process each piece of ‘confidential information’ (as defined in the particulars of claim) pertained to.

Public domain assessment – assessing whether the ‘confidential information’ was, as a matter of fact, generic and/or widespread industry knowledge within the field of quantitative investment, such that it was ‘in the public domain’.

Valuation of confidential information – determining the value of the ‘confidential information’ to a competitor, including with reference to various dates.

Retention of value – Assessing whether, and to what extent, the ‘confidential information’ is likely to retain its value over time, including over a one-year period of garden leave.

Practical utility of confidential information – Assessing whether, and to what extent, other businesses (including Citadel Securities) could utilise the ‘confidential information’ in their business activities.

The claimants acknowledge that they will, of course, give appropriate disclosure, and address these matters, as required, in their witness evidence (by people with first-hand knowledge of such matters). In his turn, the defendant will clearly be well able to address these matters himself.

For all these reasons, the claimants invite the court to dismiss the defendant’s application to adduce expert evidence. It is not necessary. It is not reasonably required. It would not even be potentially useful (which is not the test in any event). To the contrary, it is more likely to be an unwelcome distraction, both in the preparation for a speedy trial, and for the trial judge at trial. It will, in reality, serve substantially to increase costs, and for no material benefit. If, notwithstanding the claimants’ submissions, the court were against them, then directions would be needed: (i) in respect of each and every issue (which would need to be carefully defined) in relation to which the court considers that expert evidence is reasonably required, (ii) for the exchange of reports (which, contrary to the defendant’s position, should plainly come after, and not before,factual witness evidence), (iii) a joint without prejudice meeting, (iv) a joint statement, and so forth. I have already referred (in the section of this judgment dealing with case management issues) to the claimants’ post-hearing submission that if (contrary to their primary position) the court were to determine that expert evidence is reasonably required, a number of consequential matters would arise for determination at a further hearing.

In her recently filed, further written submissions, Ms Goodman begins by submitting that this is an appropriate case for a single joint expert. This would be more proportionate. Whilst the matters which that evidence would address are controversial, they are appropriate for determination by a single expert. Referencing observations of Birss LJ (with the agreement of Sir Geoffrey Vos C and Arnold LJ) in Stellantis Auto SAS v Autoliv AB [2024] EWCA Civ 609, [2024] 1 WLR 4742 at paragraphs 62 and 63, Ms Goodman points out that: (i) "the utility of single joint expert evidence is not confined to uncontroversial matters"; and (ii) separate experts may well be appropriate where there are "multiple schools of thought", but that is “a quite specific state of affairs, very different from the kinds of differences of opinion one sees with expert evidence generally”. The defendant also submits that, given the constrained time-frame before the trial is scheduled to take place in February 2026, there is considerable sense in single joint expert evidence, which will be a swifter process than the typical directions for separate expert evidence require.

Ms Goodman invites the court to hold that this is a case in which considerations of proportionality must take centre ground. The defendant submits that a single joint expert is more proportionate (as it represents a significant costs saving), and accordingly ought to be ordered in these proceedings. Two considerations arise with respect to proportionality: (i) the fact that the primary remedy which the claimants seek is unrealistic; and (ii) the parties' staggeringly different financial means. As regards proportionality, first and foremost the claimants seek injunctive relief. That is the primary remedy they seek because they say that damages would not be adequate as a remedy. The defendant submits that the injunctive relief which the claimants seek is both unrealistic and unprecedented because it would put the claimants in a better position than if there had been no misuse of the claimants’ confidential information. The claimants are seeking, in essence, for the defendant to be restrained by a non-competition covenant lasting two years beyond the end of his year’s garden leave - in circumstances where his employment contract does not itself contain any non-compete covenant. Self-evidently, the claimants will be placed in a better position than they would otherwise have been but for the defendant's actions. This is said to be unrealistic, and to lack any basis in precedent. Accordingly, considerations of proportionality ought to be tempered by the unrealistic position adopted by the claimants in these proceedings. A second consideration is the financial asymmetry between the parties. This is relevant to both limbs of the overriding objective. Ms Goodman says that the claimants' propensity, and ability, to incur eye-watering costs will be readily apparent to the court. The defendant is a private individual of limited means. A single joint expert will enable the defendant to be able to participate in the proceedings on a more level playing field. It is therefore more just, and will limit the overall costs of the proceedings.

Ms Goodman then moves to consider the five topic headings for expert evidence, as follows:

Stage in trading strategy development:

Public domain assessment:

Valuation of confidential information:

Retention of value:

Practical utility of confidential information:

Those are the competing submissions. I begin with the observation that I find it distinctly unhelpful that the claimants have not yet articulated their objections to the provision of any expert evidence that the court may order by way of a single joint expert rather than from separate experts instructed by each of the parties. On the claimants’ approach, if, contrary to their submissions, I were to order expert evidence on any of Ms Goldman’s five topics, there would be the need for a further court hearing, with the consequent further delay and expense, and recourse to scarce judicial resources, to which this would give rise. Apart from this consideration, however, the estimated costs of any expert evidence are clearly a relevant consideration for the court when it decides whether to give permission for expert evidence (as recognised by the requirement in CPR 35.4(2) to provide an estimate of such costs when any party applies for permission to call expert evidence). The form in which the expert evidence is to be given is also relevant to the procedural timetable leading to this expedited trial. The parties’ duty to help the court to further the overriding objective (pursuant to CPR 1.3) would seem to me to have required engagement between the parties, and with the court, as to the form of any expert evidence, either before the last hearing, or at least before furnishing the court with any further written submissions. The result of the claimants’ approach is that I am left in ignorance as to the claimants’ reasons for objecting to a single joint expert, even though the court squarely raised the possibility of such at the hearing (which lasted over five court hours). I am also left in a potential vacuum as to the implications of giving permission for expert evidence, in terms both of the costs and the procedural timetable leading to the expedited trial. On the material presently before me, I am of the view that a single joint expert would be appropriate to address all of Ms Goodman’s five topics. I cannot see why, on any of those topics, the potentially competing opinions of separate experts are required. To adopt a submission advanced by Mr Craig KC (at page 117 of the transcript), admittedly in opposition to the admission of any expert evidence at all: “ … it is likely to be a serious distraction from the issues and waste a significant amount of time and, frankly, make life more difficult for the trial judge”. In my judgment, on the material presently before me, if I order any expert evidence at all, the views of a single joint expert should be adequate, both for the parties and the court, subject to the opportunity to put questions to such expert in the run-up to the expedited trial. I therefore approach this application on that footing that any expert evidence will come from a single joint expert; and that the cost will be in the region of no more than £50,000 (with the possibility of up to a £10,000 uplift for VAT).

I approach this application bearing in mind the legal principles I have already formulated. I also bear in mind the overriding objective and its constituent elements. In particular, I bear in mind the need to ensure, so far as practicable, that the parties should be on an equal footing, and able to participate fully in the proceedings; the need to save expense; and the need for this litigation to be conducted proportionately, fairly, and expeditiously. In this connection, I have regard both to the nature of the primary relief sought by the claimants, in the form of an injunction imposing substantial restraints upon the defendant’s work activities, and extending for two years beyond the end of his two years’ garden leave, and the asymmetry between the parties in terms of their respective resources. I also bear in mind that the burden of proof in this case rests on the claimants; and that they are the party who resist the admission of expert evidence. That is relevant when the court considers whether it should permit expert evidence to be adduced at trial. If expert evidence is necessary to enable the claimants to prove an issue at trial, and no such evidence is adduced, then the claimant may well fail on that issue at trial. If expert evidence would merely assist in resolving an issue, then the burden of proof may have less of a part to play in the court’s decision whether or not to admit expert evidence. To this extent, the party bearing the burden of proof may face a lesser hurdle than the counter-party when it seeks to persuade the court to permit expert to be given at trial.

In the present case, the defendant seeks an order giving him permission to rely upon the evidence of Mr Colin Knight on the expert evidence issues as defined in the supporting witness statement of Mr Sheikh. Those are the five issues serially identified at paragraph 21 of that witness statement. I should record my tentative concerns about the expertise professed by Mr Knight. He describes himself as a qualified trader, with over 20 years’ experience, who has expert knowledge of the analysis of trading strategies, structured products, and so forth. However, it is clear from his career history that, for much of the last eight years (since January 2018), he has been delivering financial investigation, litigation support, and valuation services to the financial services sector, including acting as expert witness. In other words, he would appear not to have been working at what may be termed the ‘digital coal-face’, but rather at its forensic periphery. Not having seen any report from him (even in draft), or heard from him as a live witness, I say no more than that this may tend to devalue his role as an expert witness.

Against this background, I proceed to consider Mr Sheikh’s five topics in turn. In doing so, I have considered whether any confidentiality restrictions imposed during the course of this litigation in order to protect the claimants’ proprietary interests in its confidential information may serve to prevent or impede the defendant’s ability to assemble and deploy factual evidence relating to any of the issues arising in this litigation.

Stages in trading strategy development

Public domain (or industry knowledge) assessment

Valuation of confidential information

Retention of value

Practical utility of confidential information

So, for these reasons, I refuse to permit any expert evidence on any of Mr Sheik’s issues (1)-(4); but I give permission for a single joint expert on issue (5), reformulated in the terms I have indicated (or any improved formulation the parties may agree).

I invite the parties to agree, and file for the court’s approval, the terms of an order to give effect to this judgment.