The appellants, who are four young men aged between 24 and 18, bring their appeals with the leave of the full court, which was granted on 25 March 2011: (Aikens LJ, Keith and Thirlwall JJ). Reasons for the grant of leave were handed down on 7 April 2011. Leave to appeal was granted on two grounds only. One concerns all four appellants. The other was raised only by the appellant Chattoo. At the hearing of the appeal before us on 8 and 9 December 2011, Mr Henry Grunwald OBE QC, counsel for Chattoo, told the court that the second ground was not to be pursued, so we say no more about it.

At the end of the appeal hearing on 9 December 2011 we announced that the appeals would be dismissed for reasons to be given in writing. These are our reasons.

The appeals are against the appellants’ convictions after a trial before Griffith-Williams J and a jury in July and August 2009. There were two counts before the jury. The first concerned the attempted murder of Tarek Chaiboub, whom we shall refer to as “TC”. That charge was the result of a knife attack on TC on 6 July 2007. The prosecution case was that the attack had been ordered by Nigel Junior Ramsey (“N Ramsey”), who was at that time a serving prisoner. It was alleged that Michael Chattoo (“Chattoo”) and Javan Galloway (“Galloway”) were the attackers. TC was seriously injured in the attack, suffering several stab wounds, one of which punctured his liver. At the trial Chattoo and N Ramsey were convicted on that count, as was the co-accused Galloway, who is not an appellant in the present appeal.

TC was in hospital for 3 days following the attack. He was discharged on 9 July 2007. Then on 11 July 2007 at about 13.46 hours TC was shot dead outside a barber’s shop on Spital Hill in Pitsmoor, Sheffield. He was 17 years old.

At the conclusion of the trial before Griffith-Williams J, on 7 August 2009, N Ramsey, Chattoo, Denzil Emanuel Ramsey (“D Ramsey”) and Levan Menzies (“L Menzies”) were all convicted of the murder of TC (Count 2). The prosecution case was that N Ramsey had ordered that this killing should take place and that Chattoo, D Ramsey and L Menzies were all present at the shooting.

The sole extant ground of appeal is that that the court should receive new expert evidence pursuant to its powers under section 23 of the Criminal Appeal Act 1968, as amended, (“CAA 1968”), and, that upon doing so, this evidence would demonstrate that the convictions were unsafe so that the appeals must be allowed. Counsel for the appellants accepted that if the court held that it was not “necessary or expedient in the interests of justice” to receive that evidence under section 23(1), then the appeals would have to be dismissed.

At the outset of the hearing we informed counsel that we had read in advance the report of the expert, Mr Geoffrey Arnold, which was intended to form the basis of the proposed new evidence, all the other relevant expert reports that had been produced in advance of the trial before Griffith-Williams J, the relevant evidence that had been given at the trial of these appellants and the relevant expert evidence that had been adduced at a subsequent, connected trial. We had also read Griffith-Williams J’s summing-up. We therefore asked counsel to deal first with the question of whether this court should formally “receive” the proposed new expert evidence. Having heard argument on that issue the court came to the clear conclusion that it was not “expedient and in the interests of justice” within the terms of section 23 of the CAA 1968 to receive the proposed new evidence. We therefore dismissed the appeals.

N Ramsey and D Ramsey are brothers. They are cousins of a young man called Junior Liversidge. Chattoo is a friend of Liversidge. Javan Galloway is Chattoo’s cousin. At the relevant time L Menzies lived next door to the Ramsey brothers.

In 2008 all these young men were members of the S3 gang, which operated in the S3 area of Sheffield. TC was also a member of the same gang. In the first part of 2008 there was internecine strife in the S3 gang. One faction of the gang murdered Brett Blake, who was a member of the other faction of the gang. Shortly after Blake’s funeral, Junior Liversidge was stabbed by associates of the murderers of Blake.

At the trial of the present appellants before Griffith-Williams J, the prosecution case was that N Ramsey wanted TC killed because N Ramsey believed that TC was responsible for identifying to the opposite camp in the S3 gang the whereabouts of Junior Liversidge on the day that he was stabbed. The prosecution case was that N Ramsey ordered, encouraged or persuaded M Chattoo, D Ramsey, Galloway and L Menzies to murder TC, who had one foot in each of the rival camps of the gang.

The prosecution case at the trial was that on 11 July 2008, Chattoo, D Ramsey and L Menzies had gone to the barber’s shop in Spital Hill where TC was seeing a friend. There (the prosecution said) TC was shot with a sawn-off shotgun. When TC was killed by a single gunshot wound in the back. In the post-mortem examination 12 gauge wadding, including the plastic base to the wadding, was found lodged in TC’s right lung. The judge found, for sentencing purposes, that it was Chattoo who had shot TC. One witness said that there was a second weapon present, but it was never established who (if anyone) had it on him.

Ten days after the shooting, on 21 July 2008, a single barrelled 12 gauge, sawn-off pump action Beretta shotgun (“the shotgun”) was recovered by the police from Osgathorpe Park in Sheffield. It was examined by Dr Mark Robinson, a forensic firearms and ballistics expert. In its magazine (not the breech) Dr Robinson found one Lyalvale Express Magnum Game shotgun cartridge which was itself loaded with a 50 gramme load of No 1 shot. At the trial before Griffith-Williams J it was the prosecution case that the shotgun was the murder weapon.

Subsequently, Daud Ahmed and Abdi Rahman Ali were charged with assisting D Ramsey by the recovery and concealment of that sawn-off shotgun after the fatal attack on TC. It was alleged that Daud Ahmed and Abdi Rahman Ali had recovered the shotgun and held it in their possession between the day of the murder of TC until 18 July when it had been thrown away in Osgathorpe Park.

Others (apart from Daud Ahmed and Abdi Rahman Ali) were also alleged to have assisted Chattoo, J Galloway, D Ramsey and L Menzies to hide from the police after the fatal attack on TC. They were Keisha Mindley-Donaldson, Chelsea Craven, and Ahmed Yousef Warsame.

Originally there was one Indictment that encompassed all the charges against all defendants (eleven in total) arising out of the attempted murder of TC, his subsequent murder and the events thereafter. However, at a PCMH held in Sheffield Crown Court on 8 April 2009, it was ordered that this portmanteau Indictment be severed. As a result, the first Indictment contained only two counts. As already noted, Count 1 alleged that Chattoo, J Galloway and N Ramsey had attempted to murder TC on 6 July 2008 and Count 2 alleged that Chattoo, N Ramsey, D Ramsey and L Menzies had murdered TC on 11 July 2008. That Indictment containing those two counts formed the subject matter of the trial before Griffith-Williams J, which we will therefore call “the First Trial”.

For present purposes the important count in what became the second Indictment is count 2. That alleged that Abdi Rahman Ali and Daud Ahmed assisted D Ramsey, an offender, contrary to section 4(1) of the Criminal Law Act 1967. The particulars of offence stated:

The trial of the other defendants, including Abdi Rahman Ali and Daud Ahmed, took place before HHJ Keen QC in October 2009. We will refer to that trial as “the Second Trial”. It was the prosecution’s case in the Second Trial that the “firearm” in the Particulars of Offence of count 2 was the sawn-off shotgun that had been used to murder TC. Again it was the prosecution’s case for the purposes of this charge that the sawn-off shotgun that had been found in Osgathorpe Park on 21 July 2008 was the murder weapon.

There was evidence at the First Trial that, within half an hour of TC being shot, Chattoo, D Ramsey and L Menzies were taken in a taxi to 97 Norgreave Way, the home of Chelsey Craven, who was a friend of Chattoo and Denzel Ramsey. On 9 September 2008 the police searched that address. There they recovered six 12 gauge Lyalvale Magnum Maximum Game No 1 cartridges. The prosecution case at the First Trial was that the cartridge that killed TC was from the same batch as had been found in 97 Norgreave Way or that it was linked to those cartridges. A DNA sample recovered from the cartridge in the shotgun matched that of Meshack Menzies, the younger brother of L Menzies, who lived with him, although Meshack had nothing to do with the killing of TC. The prosecution said that all this evidence (viz. the fact of the defendants going to 97 Norgreave Way, the cartridges being found there and the DNA evidence) provided a “conclusive tie-in” between the shotgun that had been recovered and L Menzies and the other two accused of being at the murder scene, viz. Chattoo and D Ramsey.

The results of Dr Robinson’s examination of the shotgun recovered from Osgathorpe Park, the cartridges in it, the wadding recovered from TC’s body and the cartridges found at 97 Norgreave Way were all recorded in three statements made by him. Those statements were read to the jury in the First Trial without objection because the defence teams had decided not to call any firearms/ballistics expert in opposition to Dr Robinson.

Dr Robinson’s examination of the sawn-off shotgun recovered was undertaken with assistants. Dr Robinson and the assistants wrote notes of their findings. We have seen all the notes that were made and read carefully all the relevant ones.

Dr Robinson said in his third statement (which was prepared during the First Trial and dated 15 July 2009), that the shotgun had been recovered from Osgathorpe Park “closely wrapped in a plastic bag”. In examining the shotgun, Dr Robinson noted that at some time the barrel had been shortened to a length of 39.5 cm. The stock had also been shortened. Dr Robinson’s first action in examining the shotgun was to push a piece of cotton patch through the inside of the barrel so as to gather the contents of the barrel including any discharge residues in the gun. The cotton patch was put into a self-sealing polythene bag. Dr Robinson’s notes indicate that the cotton patch was examined under a low power microscope to see if there were any blood stains on the patch. There were none, nor were there any signs of discharge residues. Dr Robinson’s notes do not record whether any other possible residues such as swarf were found. (We will explain the significance of that below). Dr Robinson noted that light deposits of rust were present on the barrel. However, his notes do not indicate that he examined the muzzle of the shotgun. Marks or residue there might have given an indication of whether the shotgun had been fired after it had been cut down.

Dr Robinson then measured the “trigger pull” of the shotgun in the condition in which it was received. Those figures were recorded. Dr Robinson then attempted to use the shotgun to fire a live round. He found that the shotgun was incapable of discharging a cartridge. In his first statement (28 November 2008), he said that this was “due probably to a build-up of greasy deposits on the firing pin and hammer spring”: (page 9 of 15).

Dr Robinson’s assistant then stripped the shotgun and it was given a thorough clean with penetrating oil. In his first statement Dr Robinson recorded (at pages 9-10) that “after reassembly, the gun was found to have been restored to working order and has been successfully test fired”. In fact, in a note of Dr Robinson (dated 21 November 2008 and so made before his first statement, and about 3 months after the shotgun was first received by him) he noted that “after cleaning…strike does not always lock forward (frequently does not). Whether or not this occurred on receipt not specifically recorded, but fault not noticed during original trigger pull work, therefore may be result of dismantle/clean/reassemble. Not investigated further. Check whether locked by pushing on breach with rod”. In making his submissions to us Mr Grunwald attached particular significance to this entry.

As already noted, in the shotgun’s magazine Dr Robinson found a Lyalvalve Magnum Maximum Game shotgun cartridge. Dr Robinson dismantled the cartridge and found it contained a total of 50 grammes of No 1 shot and also had a Danish VP20 plastic base to the wadding. Dr Robinson reported that the average weight of the pellets was 0.25grammes. He commented in his first statement that “No 1 shot seen previously in casework and in ammunition held in the laboratory reference collection has ranged from 0.28 to 0.31 grammes”. Dr Robinson also reported that the average weight of the 11 pellets recovered from TC’s body was 0.25grammes, which corresponded to the No 1 shot from “a Magnum Game cartridge of the type” recovered from the shotgun. Dr Robinson noted that the plastic wadding recovered from TC’s body comprised “the base section and four separated leaves from a 12 gauge Danish VP20 wad of the type loaded in a Magnum Maximum Game cartridge” of the type recovered from the shotgun. He also noted that the base section of the wadding recovered bore striations consistent with having been discharged from a sawn-off shot gun.

Dr Robinson then carried out six test firings. For five of them he used cartridges which were not Lyalvale Magnum Game cartridges but HawkBest and Seller & Ballot cartridges from laboratory stock, which had the same type of VP base to the wadding as that recovered from TC’s body, viz. 12 gauge Danish VP20 plastic wadding. For the sixth he used a different wad type. (Dr Robinson confirmed that this is what he did in a statement dated 13 October 2009; therefore one that was produced after the First Trial but before the Second Trial). Only five of the cartridges could be recovered; the sixth was lost in the bullet trap. The fact that Dr Robinson did not use Lyalvale cartridges for this test is not immediately apparent from his first statement. He says (on page 12 of 15) that he examined the six cartridges recovered from 97 Norgreave Way and found they had no specific association with the shotgun. He then records, immediately below that paragraph: “I have discharged five of the cartridges during my tests”. To our minds, that gives the distinct impression that he discharged five of the six cartridges that were recovered from Norgreave Way. It is now clear that this was not the case. However, although this passage in his first statement is misleading, we are quite satisfied that this was unintentional and simply a result of poor expression. We are also quite certain that this “misleading statement” is not significant because it is agreed by Mr Arnold that the type of wadding used in the relevant test firings was of precisely the same type as that recovered from TC’s body.

Dr Robinson examined under a microscope the striations produced on the plastic bases of the wadding when the test cartridges were fired. He compared them both with one another and with the plastic base of the wadding recovered from TC’s body. He recorded (at page 11 of his first statement) that:

Dr Robinson’s opinion from the outset was, therefore, clear. As a forensic scientist, he could not say from the evidence he had that the cartridge which killed TC was fired by the shotgun that the prosecution asserted was the murder weapon.

Dr Robinson examined the six 12 gauge Lyalvale Magnum Maximum Game No 1 shotgun cartridges recovered from 97 Norgreave Way. He concluded that they were of the same type and construction as the cartridge recovered from the shotgun. He dismantled one of the six cartridges and it contained a VP20 plastic base and pellets of a similar weight to those in the cartridge recovered from the shotgun. Dr Robinson reported that a check with the National Firearms Forensic Intelligence Database disclosed that there were no records of this type of cartridge being encountered at the laboratory in criminal casework. He expressed the conclusion (at page 12 of 15 of his first statement) that “this finding provides supporting evidence for the proposition that the cartridge [recovered from the shotgun] and the cartridges recovered from 97 Norgreave Way have originated from the same source”. However, he also stated, significantly, that he could find no association between marks he found on five of the six Norgreave Way cartridges and the shotgun.

Dr Robinson compared the shot and wadding found in the cartridge recovered from the shotgun, TC’s body and 97 Norgreave Way. He concluded that the VP20 wadding recovered from TC’s body was the same type as that found in the cartridge in the shotgun and the cartridges from Norgreave Way. Dr Robinson commented (at page 12 of 15 of his first statement) that the laboratory collection held “at least 170 other types of plastic wad and numerous samples of fibre wadding, all distinguishable from the VP20 wad”. He also concluded that the No 1 pellets recovered from TC’s body were of “very similar” weight to the pellets loaded in the Lyalvale cartridges, with an average weight of 0.25 grammes per pellet. Dr Robinson commented that the weight of a No 1 pellet “might normally be expected to fall in the range of 0.28 to 0.31 grammes”. Accordingly, in his view, the pellets recovered from TC’s body and those from the other cartridges were “distinguishable from shot loaded in many other brands of No 1 cartridge (although the possibility that other brands may contain pellets of such weight cannot be discounted)” (first statement pages 12-13). He also commented that No 1 shot was encountered in the laboratory considerably less frequently than other more common shot sizes. He concluded, therefore: “Overall, the correspondence between wad type and pellet weight provides strong supporting evidence for the view that TC was shot using a Lyalvale Magnum Maximum Game No 1 cartridge of the type discovered” : (page 13 of the first statement).

Dr Robinson produced a second statement dated 9 March 2009. This dealt with an examination of the jacket that TC had been wearing when shot, because Dr Robinson had undertaken to see if he could form an opinion on the range at which TC had been shot. He concluded that the range was less than 3 feet.

At the end of March 2009, Mr David Dyson was asked by solicitors instructed on behalf of Chattoo to review Dr Robinson’s first statement. In his draft report, Mr Dyson described himself as a “peer-assessed Forensic Practitioner in the field of firearms and in the sub-specialities of ballistics, comparison microscopy and the classification of firearms”. He holds two law degrees and is a barrister. He has specialised in the examination of firearms and related items since 1980. Mr Dyson was asked in particular to determine whether it was possible to establish whether the shotgun was not the murder weapon. Mr Dyson sent a letter dated 26 March 2009 in which he summarised (for funding authorisation purposes) what he understood to be his instructions. These included: first, an examination of the shotgun and the ballistics related exhibits recovered from TC’s body; secondly, to conduct a forensic examination of the exhibits, “including microscopic comparisons of discharged cartridges and wadding”, so as to identify:

The letter goes on to list further tasks. Two are important in the context of these appeals:

Consider the forensic protocols adopted by prosecution examiner; and comment thereon as appropriate”.

In our view Mr Dyson’s summary of his tasks covers all the relevant forensic issues that needed to be investigated by him in relation to the shotgun and the cartridge found in TC’s body. Ultimately, it was accepted by counsel for the appellants that there were no deficiencies in Mr Dyson’s instructions or in the scope of the work he was asked to do.

It appears from notes made by Dr Robinson (or an assistant) that on 20 May 2009 Mr Dyson examined “items” at The Forensic Science Service, Northern Firearms Unit laboratory, in company with Dr Robinson, but that he did so “on the bench”. The note states: “No issues raised. No test-fire or microscopy”. We take that to mean that Mr Dyson did examine all the exhibits, but he did not ask to test-fire the shotgun and he did not examine microscopically the striations on the wadding of the five cartridges recovered from the test-fires that Dr Robinson had done. Nor, it seems, did he examine under a microscope the striations on the plastic base of the wadding recovered from TC’s body.

Mr Dyson produced a draft report dated 30 May 2009. He summarised its effect in a letter sent with his report to his instructing solicitors. The letter stated:

In the body of the report, Mr Dyson commented (at para 3.5) on the wadding recovered from TC’s body (exhibit CMM/19) as follows:

In the conclusions of the report Mr Dyson also noted two particular matters of importance on this appeal:

It cannot be stated with certainty that [the shotgun] discharged the fatal shot, but there is no evidence which could refute such a proposition”.

Mr Dyson did not comment in his report on the forensic protocols adopted by Dr Robinson. Nor did he comment on the rarity or otherwise of the cartridge and pellet type. However, in a fax of 30 May 2009 to his instructing solicitor, Mr Dyson commented that “Number 1 shot is not very common”.

Subsequently, on 8 June 2009, ie. before the First Trial began, and as a result of a request from his instructing solicitor, Mr Dyson and Dr Robinson had a conversation about the fact that Dr Robinson had reported that the shotgun could not fire a cartridge when he received it, probably because of a build up of greasy deposits on the firing pin and hammer spring. Mr Dyson recorded the conversation in a note dated 9 June 2009. This states that Dr Robinson told Mr Dyson that he had attempted to fire with the shotgun a number of primed cartridges of the appropriate type and calibre. Dr Robinson did not retain these tested cartridges and he said he could not recall how many attempts were made but they all failed to discharge the cartridges. Mr Dyson also recorded Dr Robinson as saying that after the shotgun was cleaned “it functioned as expected”. Dr Robinson also told Mr Dyson that a photograph had been taken of the internal mechanism before the shotgun was cleaned but it was of little use because it was out of focus. Lastly, Mr Dyson recorded Dr Robinson as saying: “It is not possible to identify at what point the deposits accrued sufficiently to prevent this operation of the [shotgun], nor how long the gun was in its practically inoperable state”.

Therefore, before the First Trial began, Mr Dyson (and, we assume, the defence legal teams) knew that Dr Robinson had carried out tests and had been unable to fire the shotgun when he first received it. The defence teams also knew that it was Dr Robinson’s view that it was impossible to identify the date at which the shotgun had become inoperable.

During the course of the First Trial, Dr Robinson produced a third statement dated 15 July 2009. Apparently this was prepared with the assistance of Mr Rhodes QC, counsel for L Menzies. This repeated the fact that the shotgun was not capable of firing when recovered by Dr Robinson and the fact that he could not say how long prior to recovery the shotgun had been incapable of firing a cartridge. The statement continues:

This statement was, we assume, read to the jury together with the other two statements, when Dr Robinson’s evidence was read on 16 July 2009. In any event, Dr Robinson’s view was known to the defence teams, given Mr Rhodes’ involvement in preparing the statement.

Mr Dyson produced a second report. Neither of them were served by the defence.

The judge summarised the evidence of Dr Robinson concerning the shotgun, the cartridges and the wadding at pp 91-94 of the transcript. He noted: (1) the gun recovered from Osgathorpe Park was closely wrapped in a plastic bag. When recovered it was loaded with one Lyalvale Magnum Maximum Game No 1 shot cartridge. (2) The wadding recovered from TC’s body compared with the wadding from that type of cartridge. However Dr Robinson could not say that the wadding recovered from TC’s body had been fired from that shotgun. (3) The weight of the pellets in the cartridge recovered from the shotgun was on average 0.25 grammes, whereas that encountered in the forensic laboratory was normally 0.28 to 0.31 grammes so that these particular pellets were of an unusual weight. (4) The weight of the pellets recovered from TC’s body was 0.25 grammes. (5) The wadding recovered from his body was the same type as that in the cartridge recovered from the shotgun. (6) “Dr Robinson’s tests showed that the correspondence between the wad type and the pellet weight provided strong supporting evidence for the view that [TC] was shot using a Lyalvale Magnum Maximum Game No 1 cartridge”. (7) The condition of the shotgun when examined was such that it could not be fired, but when cleaned it was in working order. (8) There was no way of knowing, scientifically, what condition the shotgun would have been in on 11 July 2008. (9) A DNA sample recovered from the cartridge in the shotgun matched one taken from Meshack Menzies, L Menzies’ brother, but the former had nothing to do with the killing. (10) The six 12 gauge Lyalvale Magnum Maximum Game No 1 cartridges recovered from 97 Norgreave Way were of the same type as the cartridge in the shotgun. (11) In Dr Robinson’s opinion the cartridge found in the shotgun and those recovered from Norgreave Way had originated from the same source. (12) In Dr Robinson’s view “it could not be discounted” that the six cartridges and the single cartridge in the shotgun came from the same box of 25 cartridges.

The judge then posed this issue for the jury:

Mr Geoffery Arnold was instructed on behalf of the defendants Daud Ahmed and Abdi Rahman Ali for the Second Trial which took place in October 2009. As already noted, it was the essence of the case against them that they had assisted D Ramsey in recovering, hiding and disposing of the shotgun which was subsequently found in Osgathorpe Park that that shotgun was the murder weapon.

Mr Arnold produced a statement dated 6 October 2009. It was in the form prescribed by section 9 of the Criminal Justice Act 1967. Mr Arnold reviewed Dr Robinson’s first statement and Dr Robinson’s examination notes (although it is uncertain whether he had them all) and the relevant exhibits and did so with a view to commenting on: (i) any ballistic evidence relating to the brand of shot gun cartridge used in the killing of TC; (ii) any ballistic or tool marking showing an evidential link between the gun recovered and the death of TC; and (iii) any ballistic or tool marking showing an evidential link between the shotgun cartridge recovered with the shotgun and/or with the cartridges recovered from 97 Norgreave Way.

Mr Arnold stated that he agreed with Dr Robinson on a number of matters. First, he agreed that there was no specific agreement between the wadding recovered from TC’s body and the test wads discharged from the shotgun. Secondly, he agreed with Dr Robinson’s statement that he was unable to say whether or not the wadding recovered from TC’s body had been fired from the shotgun. But, Mr Arnold went on to say that, in his view, the lack of specific agreement of the striations “indicated that the shotgun was not the [murder] weapon”. Thirdly, he agreed that the cartridges recovered from Norgreave Way were similar to the cartridge recovered from the shotgun and that they are Lyalvale 12 bore Express Magnum Maximum Game cartridges. Fourthly, Mr Arnold agreed that the plastic wad recovered from TC’s body was similar in type and manufacture to the wads in the cartridges recovered from the shotgun and Norgreave Way. Fifthly, Mr Arnold agreed that the pellets found in TC’s body were of similar size to those in the recovered cartridges. He further accepted that such pellets may well be distinguishable from shot loaded in many brands of No 1 shotgun cartridges. However, he believed that they were similar in weight to other European and US brands.

Mr Arnold’s first main difference of view with Dr Robinson was on whether the cartridge recovered from the shotgun came from the same source as the cartridges recovered at 97 Norgreave Way. Mr Arnold said that 45,000 cartridges of that type had been produced in the 4 years since their introduction and up to the death of TC. Mr Arnold suggested that, without supporting evidence of traces, finding seven of the cartridges in two separate locations did not equate to supporting evidence that they all originated from the same source, other than the fact that they originated from the same manufacturer.

Secondly, although Mr Arnold agreed that the plastic wad recovered from TC’s body was similar in type and manufacture to the wadding in the cartridges recovered from Norgreave Way and the cartridge in the shotgun, he did not agree that this correspondence between the wadding type and the correspondence in pellet weight provided “strong” scientific supporting evidence for the view that TC was shot using a Lyalvale Magnum Maximum Game No 1 cartridge of the type recovered. In Mr Arnold’s view, the cartridges, pellets and waddings were far from rare and the pellet-wadding combination could have originated from another cartridge manufacturer, not just Lyalvale.

Therefore Mr Arnold’s conclusions were: (1) that there was no conclusive evidence that the cartridge used to kill TC was a Lyalvale cartridge (2) There was no evidential link between the shotgun recovered and the killing of TC. (3) He agreed with Dr Robinson that there was no correspondence between the wad found in TC’s body and the wads produced in the test-fires with the shotgun. In Mr Arnold’s view the recurring striations on the test wads were so distinct that, had the shotgun been the murder weapon he would have expected those striations to be present to some degree on the wad recovered from TC’s body. (4) There was no evidential link between the shotgun cartridge recovered with the shotgun and the cartridges found at 97 Norgreave Way, other than the fact that they all originated from Lyalvale and were similar cartridges.

At the Second Trial Dr Robinson gave evidence for the prosecution. We have read the transcript. In the course of a conspicuously skilled cross-examination by Mr Holland on behalf of Ahmed, Dr Robinson accepted: (1) that the grease accumulations on the shotgun that made it impossible to discharge a cartridge when he first received it had probably occurred over a long period of time. (2) He could not state what condition the shotgun was in either on or prior to 11 July 2008. (3) There was no scientific means of ascertaining when the shotgun was last fired. (4) It was reasonable to say that the “build-up” of greasy deposits seen on the shotgun on receipt had occurred over a period of time. (5) He was unable to say when the gun stopped working. (6) The condition of the barrel of the shotgun (greasy deposits but no soot or other “fouling”) suggested that it had been cleaned since last being fired but there had been neglect of maintenance of other parts of the gun that rendered it inoperative. (7) When the shotgun was first examined, the unfired cartridge was not in the chamber - or breech - but in the magazine. There was no spent cartridge in the breech, so that cartridge had been removed once the shotgun was fired and no new cartridge had replaced the spent one in the breech, or, if it had, then that cartridge had also been removed. (8) Although there was some limited agreement on the marks (striations) on the wads created in test firing cartridges which were from a different manufacturer, there was no agreement between those striations and those in the wadding recovered from TC’s body. Therefore he could not say whether the latter wadding had been fired from that shotgun. (9) Later, he said the “specific signature” found in the markings on the 5 test firing wads was not found also on the wadding recovered from TC’s body. (10) His evidence did not provide any evidence that the shotgun was the gun used to kill TC. (11) In the absence of the spent cartridge case he was unable to say whether the shotgun was the murder weapon.

We note at this stage, first, that points (1) – (6) go no further than the position as known to the defence teams in the First Trial following Dr Robinson’s third statement of 15 July 2009 (at the latest); secondly that points (8) and (9) repeat Dr Robinson’s position as set out in his first statement; thirdly, (10) and (11) repeat what Dr Robinson had said in his third statement made on 15 July 2009.

Mr Arnold also gave evidence in line with his report.

The jury acquitted Ali and Ahmed of assisting Chattoo. The submission of the appellants on this appeal is that their acquittal must have been because the jury was not satisfied that the shotgun recovered on 21 July 2008 was the murder weapon. That conclusion, it is said, must have been reached largely, if not wholly, as a result of the evidence of Mr Arnold and the concessions made by Dr Robinson in his cross-examination.

Mr Arnold’s report produced for the purposes of this appeal is dated 14 November 2011 and is attached to his section 9 statement of 15 November 2011. This builds on evidence that he gave at the Second Trial before HHJ Keen QC. The report (1) examines the forensic evidence in relation to the shotgun and ammunition associated with this case; (2) comments on the forensic methodology adopted in the forensic examinations, particularly that of Dr Robinson and Mr Dyson; (3) comments on the comparison macroscopy; (4) comments on the condition of the shotgun; and (5) comments on the reports and witness statements of Dr Robinson, Mr Dyson and Mr Jackson, who is the Sales Manager of Lyalvale Express Cartridges, who gave a statement dated 29 September 2009.

The conclusions of this report criticise Mr Dyson in failing to deal with various matters. First, Mr Arnold critics Mr Dyson for failing to note the fact that the suppliers of the No 1 size shot, Locatelli, supply many other cartridge makers other than Lyalvale, as do the suppliers of the VP20 plastic wadding and, also, that the some 45,000 Lyalvale Magnum Maximum Game No 1 shotgun pellets had been produced in the four years prior to the shooting. Secondly, he criticises Mr Dyson for failing to state that there was no evidential link between the shotgun and the murder other than the similarity with the pellet size and the wad type (compared with that in the cartridge found in the magazine of the shotgun when it was recovered). Thirdly, Mr Dyson is criticised for not pointing out that the shotgun did not work when recovered and that there was no means of telling when it had last worked and for not reporting on the problems of ejecting discharged 76 mm cartridges or the fault with the fore-stock frequently not locking. Fourthly, he criticises Mr Dyson for not conducting a comparison macroscopy examination of the striations on the test-fire wads with that recovered from TC’s body and for impliedly accepting that there was a degree of association which Mr Arnold believed was not present. In Mr Arnold’s opinion, this lack of correspondence did mean that there was no connection between the shotgun and the fatal shot. Lastly, Mr Arnold criticises Mr Dyson for not using his opportunity to examine the exhibits and to test the quality and validity of the forensic evidence to good effect.

In relation to Dr Robinson, Mr Arnold’s chief criticisms are: (1) that Dr Robinson could not find any association between the shotgun and the scene of the shooting on 11 July 2008. (2) The wadding recovered from TC’s body had none of the identifying marks that were found on the 5 test-fires with similar cartridges using this shotgun. In Mr Arnold’s view that gave strong support to the hypothesis that the wadding recovered from TC’s body was NOT fired from this shotgun. (3) The prosecution’s case that the size and weight of the shot was unusual or unique was wrong because it was now the standard size/weight of European suppliers. (4) The only similarity between the wadding recovered from TC’s body and the test-fire wadding was that they were all fired from a shotgun with barrel irregularities. (5) It was highly probable that the shotgun was in the same condition on 11 July 2008 as it was when it was recovered on 21 July; if so then it was not capable of firing on the earlier date when TC was murdered. (6) Although the shot and wad combination (as recovered from TC’s body) was consistent with that of a Lyalvale Magnum Maximum Express Game Number 1 cartridge, the conclusion that the cartridge recovered from TC’s body was the same type did not necessarily follow. The combination was “limited supporting evidence” for that conclusion. (7) There was no evidence that Dr Robinson considered the hypothesis that the shotgun did NOT fire the wadding/shot recovered from TC’s body. As a scientist he should have done so. (8) Although Dr Robinson stated in his first statement that he could find no association between the cartridges recovered from Norgreave Way and that in the shotgun, in his third witness statement he canvassed the possibility that the 25 cartridges in the standard box of ammunition could have been distributed amongst a number of addresses within a given small geographical area. Mr Arnold agreed with the last point but drew the opposite conclusion, namely that “for this cartridge within this area at this time it was a popular cartridge”.

Mr Arnold’s conclusions in his report for this appeal are: (1) there is no direct forensic evidence between the wad found in TC’s body and the shotgun. Alternative hypotheses cannot be dismissed. (2) There was no association between the shotgun and the crime scene. (3) As all the experts agreed, there was no direct association between the striations on the wadding of the test-fire cartridges and the wadding recovered from TC’s body. That lack of correspondence gave “strong support to the hypothesis that [the cartridge recovered from TC’s body] was not discharged from the shotgun”. (4) The alleged uniqueness of the size of the shot and the type of the wadding is based on “unsound data and is therefore unreliable”. (5) It is highly probable (in his opinion) that the shotgun was in the same condition when abandoned as when recovered and so was incapable of discharging a cartridge. There was no evidence to refute the hypothesis that it was incapable of discharging on the day of the murder. (6) The shot size and wad correspondence combination was only “limiting supporting evidence”, not “strong supporting evidence” that the murder cartridge was fired from the shotgun. (7) Dr Robinson failed properly to consider alternative hypotheses.

Mr Grunwald QC, for Chattoo, made the principal submissions on behalf of all the appellants. In summary he submitted that the prosecution case that the shotgun was the murder weapon was a crucial issue at the trial. Thus, if, as in the Second Trial, the jury in the First Trial had not been satisfied that the shotgun was not the murder weapon, then there would not have been what the prosecution called the “conclusive tie-in” between the shotgun that had been recovered, L Menzies and the other two accused who were alleged to have taken part at the murder scene, viz. Chattoo and D Ramsey.

Next Mr Grunwald submitted that the effect of the proposed evidence of Mr Arnold was, first, that Dr Robinson’s first statement was misleading about which cartridges were used for the test-firing to see whether the striations on the wads of those tests corresponded to those found on the wad recovered from TC’s body. He submitted that the fact that it was now known that it was not the Lyalvale cartridges recovered from Norgreave Way that were used but non-Lyalvale cartridges meant that it could now be said that the cartridge that killed TC was not fired from the shotgun. Secondly, he emphasised that it was not known at the First Trial that the gun was not in full working order, even after it had been cleaned. That only came to light once all Dr Robinson’s notes had been disclosed. Dr Robinson did not draw Mr Dyson’s attention to that fact before the First Trial. If that fact had been known, it would have given greater force to the argument that the shotgun could not have been in working order on 11 July 2008. Thirdly, Dr Robinson’s opinion that the correspondence between the wad type and pellet weight (as between the cartridge recovered from TC’s body and the cartridge found in the magazine of the shotgun) was “strong supporting evidence” that TC was shot using a Lyalvale Magnum Maximum Game No 1 cartridge of the type recovered was now not tenable, as Dr Robinson had conceded in re-examination in the Second Trial and had confirmed in his statement of 22 July 2011 which was produced for this appeal.

Fourthly, Mr Dyson did not properly carry out the work he himself identified should be done; if he had done more then the defence teams at the First Trial would have been better able to challenge Dr Robinson. In particular, Mr Grunwald relied on the criticism Mr Arnold made of Mr Dyson that he did not use his opportunity to examine the exhibits and to test the quality and quantity of the forensic evidence to good effect. Had he done so then Dr Robinson would have had to have modified his views at the First Trial, as he was forced to do at the Second Trial. Fifthly, it was not known at the time that Dr Robinson had done the exercise of pushing a piece of cotton patch through the inside of the barrel so as to collect the contents of the barrel, in order that any discharge residues in the gun should be collected. If that had been known then Mr Dyson could have asked questions about any presence of swarf. If any swarf had been present that would have suggested that the shotgun had not been fired since the barrel was cut down. Sixthly, it is clear (from the notes of Dr Robinson/his assistant dated 20 May 2009) that Mr Dyson did not do any microscopic examination of any of the wadding striations. If he had done that examination it would have demonstrated the lack of any connection between the shotgun and the wadding recovered from TC’s body. In short, Mr Dyson failed to do a proper job and the appellants were at a grave disadvantage as a consequence.

Mr Hawes QC, also appearing for Chattoo, added that the lack of any association between the striations found on the test-fire cartridge wadding and that recovered from TC’s body was emphasised by the terms of the email that was sent by Dr Robinson to the South Yorkshire police on 9 October 2009 (i.e. before the Second Trial). This indicated that Dr Robinson had considered whether the “lesser degree of association between the crime [wad] and the tests [wads] allowed us to eliminate the gun from the enquiry or at least provided evidence to indicate or suggest that the gun was not involved”. The email states that Dr Robinson concluded that no such association could be made and that “…it was simply not possible to state from an examination of the marks whether or not the wad [recovered from TC’s body] had been fired by the [shotgun]”.

Mr Rhodes QC, on behalf of L Menzies, submitted that the facts (a) that Dr Robinson had performed a “pull-through” (with a cloth) of the shotgun’s barrel but had undertaken no examination to see what gun residues were present, and (b) there were no tests for swarf, were not known at the time of the First Trial. They were important factors which, if known, could have led to further cross-examination of Dr Robinson at the First Trial. He submitted that this demonstrated that Mr Dyson had failed to investigate matters which could have assisted in showing that the shotgun was not the murder weapon.

For his part, Mr Rhodes accepted that Mr Dyson was not incompetent, but he submitted that Mr Dyson had failed to do what he should have done as an expert. In particular he had failed to deal with the lack of correspondence of the striations and he had failed to deal with the fact that the gun was inoperable when first examined by Dr Robinson as a result of a build up of grease.

Mr Bourne QC, for D Ramsey and Miss Elizabeth Marsh QC, for N Ramsey, adapted the submissions of Mr Grunwald, Mr Hawes and Mr Rhodes. The submission of all the appellants’ counsel was that, in the circumstances, it was therefore necessary or expedient in the interests of justice that this court receive the evidence of Mr Arnold.

We think that the following issues arise on this appeal: (1) when an appellant requests the Court of Appeal to receive fresh expert evidence, what factors ought this court to consider? (2) In this case, are the circumstances such that this court ought to receive Mr Arnold’s evidence because it is “necessary or expedient in the interests of justice” to do so, within the terms of section 23(1) of the CAA 1968, as amended.

Section 23(1) and (2) of the Criminal Appeal Act 1968, as amended by the Criminal Appeal Act 1995 and the Criminal Justice and Immigration Act 2008, provide as follows:

The application of these provisions to a case where an appellant wishes this Court to receive expert evidence on his behalf that was not adduced at his trial has been considered in a number of cases in this Court over the last 15 years. The following are of particular importance: R v Jones [1997] 1 Cr App R 86 (see page 93), R v Kai-Whitewind [2005] EWCA Crim 1092 (see [96] and [97], which paragraphs are not reproduced in [2005] 2 Cr App R 31), R v Meechan [2009] EWCA Crim 1701 (see [1] and [23]) and R v Henderson, Butler and Oyediran [2010] 2 Cr App R 24 (see [3] and [4]).

The principles that can be derived from these cases, at least so far as are relevant to this appeal, are: (1) section 23 is applicable to exert evidence, although it is unlikely that the section was framed with expert evidence prominently in mind. (2) The crucial test in deciding whether this Court will receive evidence on appeal which was not adduced at the trial below is the overall test set out at the start of section 23(1), viz. whether it is either necessary or expedient in the interests of justice to receive the evidence. This applies equally to expert evidence as it does to factual evidence. (3) In deciding whether to receive expert evidence that was not adduced at the trial below, the Court of Appeal must consider all the factors set out in section 23(2). (4) Save in exceptional circumstances, the Court of Appeal will not permit an appellant to mount on appeal an expert case which, if sound, could and should have been advanced before the jury; to do so would subvert the trial process. (5) Further, save in the rarest of circumstances, the Court of Appeal will not permit an appellant to advance the same expert case but with a different and additional expert, because that, too, would undermine the trial process, rendering it little more than a dress rehearsal for what would then become “the proper performance” of the expert evidence in the Court of Appeal. That is not the purpose of this Court’s jurisdiction to receive evidence on appeal. (6) Save in exceptional circumstances, the Court of Appeal will not permit an appellant to rely on further expert evidence when expert evidence in the relevant area and on the same material was obtained for use in the trial below, but the defence chose not to deploy it, because it assisted the prosecution (either wholly or in part). In such a case, an appellant who had decided not to call expert evidence at the trial should not be in any better position than an appellant who had called expert evidence at trial.

In relation to point (6) above, it seems to us that the Court of Appeal might accept that there were exceptional circumstances where e.g. it is demonstrated that the expert instructed for the trial was incompetent or that, in considering the expert evidence, the appellant’s legal team acted in a way that no reasonable lawyer or lawyers could act. But the particular circumstances of each case will determine this Court’s approach to whether it will be necessary or expedient in the interests of justice to “receive” the fresh evidence.

We accept that Mr Arnold’s evidence is capable of belief and that it would have been admissible at the trial. The reason for not adducing Mr Arnold’s evidence at the trial is simply that he was not the expert who was instructed at the time: Mr Dyson was. Mr Arnold was subsequently instructed quite independently by those acting for Ahmed and Ali in the Second Trial. We think that this factor, together with the issue of whether Mr Arnold’s evidence would afford any ground for allowing the appeal have to be considered in the context of the overall question of whether it is necessary or expedient in the interests of justice to receive Mr Arnold’s evidence.

So we ask ourselves the question: what are said to be the significant points that emerge from Mr Arnold’s proposed evidence. We think that they are very limited indeed. First, there is the fact (not known to the defence teams until after the Second Trial) that even when the shotgun had been cleaned, there were problems about it working (which Dr Robinson thought might be attributable to the way it had been cleaned). But that is not of importance compared with the principal fact, known to Mr Dyson after his conversation with Dr Robinson on 9 June 2009, that the shotgun could not fire at all before it was cleaned by Dr Robinson. Mr Dyson reported that fact to the defence teams of the present appellants well in advance of the First Trial. Mr Dyson knew and Dr Robinson confirmed in his third statement (of 15 July 2009, during the First Trial) that it was not possible to identify how long the shotgun was in its practically inoperable state. In his third statement Dr Robinson accepted that he could not say whether or not the shotgun was used in the murder of TC. That fact was known to the defence teams because Mr Rhodes was involved in the preparation of that statement the day before Dr Robinson’s evidence was read to the jury. There was no application to cross-examine Dr Robinson on that or any other issue.

Secondly, there is the fact (which we will assume was not known to the defence teams of the present appellants until after the Second Trial) that Mr Dyson did not microscopically examine the striations on the test-fire wadding and that recovered from TC’s body. However, Mr Dyson saw all the items “on the bench” in Dr Robinson’s laboratory and Mr Dyson had been specifically instructed to examine microscopically if necessary. Mr Dyson is a very experienced forensic scientist. He was aware of the conclusion of Dr Robinson (at page 11 of his first statement) that there was no specific agreement between the striations on the test fired wadding and that recovered from TC’s body and that, therefore, Dr Robinson was unable to say whether or not the wadding recovered from TC was fired from the shotgun. We regard Mr Dyson’s decision not to do further microscopic investigation of the striations as both perfectly understandable and proper in the circumstances. In the light of Dr Robinson’s very clear conclusion, there was no need for him to do the microscopic examination.

Thirdly, there is Mr Arnold’s view that the fact that the pellet weight and the type of plastic base to the wadding (VP20) recovered from TC’s body was the same as that of the cartridge recovered from the shotgun magazine and the cartridges taken from Norgreave Way does not provide “strong supporting evidence” that TC was shot using a Lyalvale Magnum Maximum Game No 1 cartridge of the type recovered from the shotgun. His assessment is that it is only “limited supporting evidence”: see para 214 of his report produced for this appeal. This difference of view is based on Mr Arnold’s assessment of whether the pellet weight (of 0.25 grammes) and the VP20 type of plastic base was common. But, even accepting Mr Arnold’s analysis (which we are sceptical about, particularly given Dr Robinson’s statement that No 1 shot is encountered in the forensic science laboratory – i.e. specifically in connection with crime – less frequently than other more common shot sizes), the result is only a difference of expert opinion on the strength of the supporting evidence. It amounts to no more than a difference of emphasis by two experienced expert forensic scientists. Mr Dyson took the same view as Dr Robinson. Mr Dyson’s view cannot be described as perverse or unreasonable.

Fourthly, Mr Arnold emphasises the fact that, in his view, on Dr Robinson’s own investigations, (a) he (Dr Robinson) could find no association between the wadding recovered from TC’s body and the shotgun; (b) he could find no association between the crime scene and the shotgun; (c) he could find no association between the appellants and the shotgun and (d) he could find no association between the appellants and the wadding recovered from TC’s body. However, (a) and (b) are clear from Dr Robinson’s own evidence given at the First Trial. Points (c) and (d) depend on the view taken of the facts concerning the type and nature of the cartridges recovered from Norgreave Way, the cartridge recovered from the shotgun and that recovered from TC’s body. Dr Robinson had expressed his expert view on this. Mr Dyson had not been prepared to disagree with it. Mr Arnold does disagree, but this amounts to no more than a difference of view. Ultimately, whether there was a connection or not was for the jury to decide on all the evidence put before them.

Lastly, there is the point that Dr Robinson’s first statement is misleading as to which cartridges he used for his test-firings which were done to enable him to compare the striations on the plastic base of the wad recovered from TC’s body and those of the test-firings with the shotgun. As already noted (see [25] above), in our view Dr Robinson’s statement is misleading, but unintentionally so. The key points of fact are that, first, the type of wadding used in the test-firings was precisely the same as that recovered from TC’s body and, secondly, that Dr Robinson found no specific agreement in the striations. Hence his clear conclusion at page 11 of his first statement that he was unable to say whether or not the wadding recovered from the body of TC was fired from the shotgun. In short, the fact that Dr Robinson’s statement was unintentionally misleading is not material.

Having carefully considered all the criticisms and points made by Mr Arnold, we are very doubtful indeed as to whether his evidence can be said to afford any ground for allowing these appeals. It amounts to no more than a difference of emphasis on the effect of the forensic examination of the materials and surrounding circumstances.

In our view this is clearly a case where it is neither necessary nor expedient in the interests of justice to receive the evidence of Mr Arnold on these appeals. First, we are entirely satisfied that Mr Dyson was and is a properly qualified forensic scientist who neither is nor was incompetent; nor did he fail in the tasks he was instructed to perform on behalf of the appellants for their trial. His instructions were clear. How he examined the exhibits and the judgments he formed on the questions he was asked to consider having examined all the materials are all matters of expertise. He effectively agreed with the expert views of Dr Robinson. Secondly, in our judgment Mr Dyson’s conclusions were entirely reasonable. He could have asked to see Dr Robinson’s notes and he could have undertaken more microscopic examinations. He might have formed a different view on whether the No 1 shot was uncommon. But his view, based upon years of experience as a forensic scientist and a proper examination of the material at the laboratory, was perfectly reasonable. Thirdly, Mr Dyson knew, at the latest after his conversation with Dr Robinson on 8 June 2009, that it was not possible to say at what point the greasy deposits had accrued sufficiently to prevent the operation of the shotgun or how long it was in its inoperable state. That information was known to the defence teams before the First Trial started. It could have been put to Dr Robinson, as it was in the Second Trial, that it had to follow from this conclusion that, as a forensic scientist, he could not say whether the shotgun had been the murder weapon because he could not say whether it was in a working condition on 11 July 2009. The defence teams in the First Trial took the decision not to question Dr Robinson on that point or on any other point.

Fourthly, in our view the defence teams at the First Trial had all the necessary materials to have conducted a cross-examination of Dr Robinson along the lines that was conducted by Mr Holland at the Second Trial. They chose not to do so. No one suggests that defence counsel at the First Trial acted other than reasonably and we emphasise that we do not criticise them for the decisions that they took. Fifthly, for reasons already discussed, the “misleading” statement and the fact that there were still problems firing the shotgun after it had been cleaned are not material.

This is a case where, as a result of skilled cross-examination of Dr Robinson at the Second Trial, the defence teams in the First Trial have concluded that Mr Arnold’s expert evidence would have been better than that of Mr Dyson at that trial. To permit its reception on appeal would be to subvert the trial process, would be to allow the appellants to run an expert case which they chose not to pursue at trial and would go beyond the jurisdiction of this Court to receive new expert evidence on appeal.

For all these reasons we concluded that it was not necessary and would not be expedient in the interests of justice to receive the evidence of Mr Arnold and so the appeals had to be dismissed.