Siddiqui & Anor v Council of London Borough of Hillingdon

Laburnum Grove in Ruislip, Middlesex is a small development of residential properties undertaken in about 1980 or 1981 by a company called Matthew Homes Ltd. (“Matthew”). In this judgment I shall call that development “the Development”. The Development was constructed on the site (“the Site”) of a property formerly known as Bury Street Farm. It was common ground before me that the soil underlying the Site is predominantly London Clay. London Clay can include sand lenses, which are pockets of sand surrounded by clay. London Clay is susceptible to changes in volume as a result of the presence or absence of moisture. In laymen’s terms, it shrinks in the absence of moisture, but swells, if below its natural moisture content, if made wet.

The Development involved the construction of thirteen houses and associated garages on thirteen plots. A road called Laburnum Grove was constructed to afford access to each of the plots. That road is a cul-de-sac. The plots laid out for the purposes of the Development were numbered consecutively from the South-West corner of the Site in a curve towards the North-West, round to the North-East and then back towards the South-West. At the North-East side of the Site, abutting the North-East boundary, three plots were laid out, respectively numbered 8, 9 and 10. In this judgment I shall refer to those plots, respectively, as “Plot 8”, “Plot 9” and “Plot 10”. Upon Plot 9 were constructed a house, to which I shall refer in this judgment as “House 9”, and a garage, to which I shall refer in this judgment as “Garage 9”. Upon Plot 10 were constructed a house, to which I shall refer in this judgment as “House 10”, and a garage, to which I shall refer in this judgment as “Garage 10”.

On the North-East side of Plot 8, Plot 9 and Plot 10 lay Ruislip Wood (“the Wood”). The Wood is an area of ancient woodland which has existed for many centuries. Its present extent is some 800 acres and it is apparently the largest area of unbroken woodland in London. The freehold owner of the Wood is the Council of the London Borough of Hillingdon (“the Council”).

On the South-East Plot 10 abuts the curtilage of “The Plough” public house (“the Public House”).

Mr. Moiz Siddiqui purchased Plot 9 in about October 1981 immediately after the construction of House 9 and Garage 9. He purchased the property in his sole name, but on 1 September 1982 he transferred the freehold title to his wife, Ishrat, and she remains the freehold owner of Plot 9.

Mr. Bhajan Sohanpal purchased Plot 10 in 1986 and he is the freehold owner of that property.

On a number of occasions over the years, starting in fact soon after Mr. and Mrs. Siddiqui moved into House 9, they noticed cracks in the structure. It will be necessary to consider the history of damage to House 9, and, indeed, to Garage 9, in some detail, but at this stage it is sufficient to record that on three occasions, respectively in 1988, 1992 and in 1999, significant work was undertaken with the aim of remedying the causes and symptoms of the apparent defects in House 9. The action brought by Mr. and Mrs. Siddiqui against the Council (“the Siddiqui Action”) was in respect of the works undertaken in 1999. In short what was said was that the necessity for the works undertaken in 1999 arose as a result of the action of the roots of oak trees in the Wood causing subsidence of the soil under House 9 and Garage 9 and consequent damage. That action of the trees roots was said to amount to a nuisance for which the Council was in law liable to Mr. and Mrs. Siddiqui.

It does not appear that House 10 suffered from any structural problems until some time in 1995. However, damage was noticed in 1996 by Mr. Sohanpal and works were undertaken to remedy that damage in 1998. The cause of the damage which necessitated the undertaking of those works was again said to be the action of the roots of oak trees in the Wood resulting in subsidence of the soil under House 10. In the action brought by Mr. Sohanpal against the Council (“the Sohanpal Action”) Mr. Sohanpal sought recovery from the Council of the cost of the works undertaken in 1998, again on the ground that the alleged action of the tree roots was in law a nuisance for which the Council was responsible.

Because of the possibility of common questions of fact arising in both the Siddiqui Action and the Sohanpal Action I ordered that the two actions should be tried together.

The Council disputed liability both in the Siddiqui Action and in the Sohanpal Action. In essence it contended that the probable cause of the damage of which complaint was made in each case was heave of the underlying soil, not subsidence, and thus not the result of any encroachment of tree roots from the Wood. However, it was strongly urged upon me by Mr. Timothy Lord, who appeared on behalf of the Council, that it was not for the Council positively to prove any cause of any damage. Rather it was for the Claimants in each action to prove positively that the cause of the damage of which they respectively complained was the action of roots of trees in the Wood. In support of that submission, which seems to me to be self-evidently correct, Mr. Lord reminded me of the decision of the House of Lords in The Popi M [1985] 2 All ER 712, a case in which the issue was whether the sinking of a ship had been caused by a “peril of the seas”, and was thus covered by insurance. The only substantive speech was that of Lord Brandon of Oakbrook. At page 714E-G he said:-

It was also contended on behalf of the Council that, if the cause of the damage complained of in the Siddiqui Action or of that complained of in the Sohanpal Action was the action of roots of trees in the Wood, it was not reasonably foreseeable that the roots of the relevant trees would cause the damage. It was further contended that in any event the Council should have been afforded an opportunity in each case, which it was not, to abate the nuisance. I shall return to these contentions later in this judgment.

Quantum was agreed, subject to liability, in both actions. In the Siddiqui Action the agreed cost of remedial works was £110,000, of which £200 - £300 was agreed to be referable to repairs to Garage 9, and it was agreed that a sum of £500 should be paid, if liability was established, in respect of general damages. In the Sohanpal Action the agreed cost of remedial works was £98,445, and again it was agreed that a sum of £500 should be paid, if liability was established, in respect of general damages.

It was common ground before me that in a case in which subsidence has been caused by the action of tree roots what happens is that tiny, hair-like roots growing out from, and usually at the end of, more substantial fibrous roots, extract moisture from the soil. As that happens a soil susceptible to alteration in volume as a result of the abstraction of water, such as London Clay, will shrink. That shrinkage will reduce the support which the soil provides to structures built upon it, and that reduction in support may cause the whole, or part, of the structure to sink. Differential sinking typically causes damage to a structure. As the whole process is dependent upon the abstraction of water by tree roots, in the case of deciduous trees it can only happen during the growing season. In Southern England the growing season is typically from about April to about September. The process of abstraction of water by tree roots, if it is to affect the stability of the soil as a support for structures, must cause a reduction in volume, which in a clay soil can occur by a reduction in moisture content – essentially drying out the soil. That process is technically called “desiccation”. Unless desiccation has occurred the cause of damage to a structure built upon a clay soil cannot be the extraction of water by tree roots.

Heave is essentially the opposite of subsidence on a clay soil. It is the consequence of re-hydrating a desiccated soil. Thus for it to be the occasion of damage to a structure built upon the relevant soil, that soil must be desiccated at the time of construction. A typical cause of soil being desiccated at the time of construction is the removal of vegetation from a clay soil shortly before construction operations commence. The sources of water which can prompt re-hydration of a desiccated soil can be many and various. However, rainwater as such will, according to the evidence of Dr. Frank Hope given at the trial, which I accept, only affect the upper 50 centimetres to one metre of the ground. For re-hydration to occur at lower depths the source or sources of water must themselves be in the ground.

As the degree of movement caused by subsidence or heave on a clay soil is often not very great in absolute terms, it is frequently not possible easily to detect whether a structure thought to have been damaged by one or the other has gone up or gone down. If it can be shown to have gone down, that must, in the type of case now under consideration, be as a result of subsidence. If it can be shown to have risen, that, conversely, must be as a result of heave.

In the absence of evidence that a damaged structure had definitely sunk or definitely risen what, in simple terms, one would be looking for in any investigation of ground conditions in the context of damage thought to be caused either by subsidence or by heave was evidence of the absence of moisture from the soil. Lack of moisture in the ground indicates tree root action, and thus the possibility of subsidence, whereas no lack of moisture indicates that the cause of the damage cannot be subsidence, but might well be heave. As heave occurs as a soil which has been desiccated re-hydrates a degree of desiccation is not uniquely diagnostic of subsidence, but subsidence cannot occur without desiccation.

On 18 July 1969 the area of the Site was photographed from the air by Aerofilms Ltd. (“Aerofilms”). The relevant photograph was submitted to Mr. D. A. Simmons of Aerofilms, a chartered surveyor, for interpretation. His brief was to plot the locations of the trees shown on the photograph on a copy of an Ordnance Survey map which showed the Site after completion of the Development, and to estimate the heights of the trees shown. The accuracy of the work of Mr. Simmons was not in dispute before me. Mr. Simmons allocated to each tree which appeared in the photograph a number. I shall refer to the trees which are relevant for present purposes using the numbering adopted by Mr. Simmons.

On Plot 9 there was, on 18 July 1969, one tree, Tree 39, the height of which was 1.8 metres. At the trial it seemed to be common ground that Tree 39 was probably an apple tree, as it was known that there had been an orchard on the Site, although in a different part of it. Tree 39 was within the footprint of House 9, meaning by that that it stood on soil now under House 9, towards the left hand side, viewed from the road, and midway between the front and the back of House 9.

On Plot 10 there were five trees on 18 July 1969. Tree 38 was at the rear left hand corner of the footprint of House 10 and stood to a height of 5.1 metres. Tree 36 was just outside the footprint of House 10 at the rear right hand corner and stood to a height of 6.3 metres. Tree 35 was to the front right hand side of the footprint of House 10 and stood to a height of 4.9 metres. Tree 34 stood to the front, road, side of the footprint of Garage 10 to a height of 5.9 metres. The last tree within Plot 10 was Tree 37 which stood to the rear on the right hand side, viewed from the road, of the footprint of House 10, to a height of 7.1 metres.

In the grounds of the Public House immediately to the rear North-East corner of the footprint of Garage 10 on 18 July 1969 was Tree 23. Tree 23 at that time stood to a height of 12.9 metres.

In the Wood on the North-East side of Plot 9 on 18 July 1969 there were three trees adjacent to the boundary. Tree 41 stood almost at the point at which the boundary between Plot 9 and Plot 10 was later placed. It was 14.9 metres high. Not far from Tree 41, moving in a North-North-Westerly direction, was Tree 42, which stood to a height of 17.7 metres. Continuing in the same direction, but further away from the boundary with the Site, was Tree 43, the height of which was 19.1 metres.

To the North-East of Plot 10 on 18 July 1969 Tree 40 stood in the Wood to a height of 14 metres.

The trees on Plot 9 and Plot 10 were all removed at some point prior to the commencement of the Development.

In advance of the commencement of the Development a Mr. Jon Chamberlain was commissioned to undertake a soil investigation upon the Site. He dug three trial pits, the locations of which were shown on a rather crude sketch which was put in evidence. Doing the best one can, the nearest trial pit to Plot 9 and Plot 10 was Trial Pit 2, which seems to have been dug approximately in the subsequent location of Plot 8. Mr. Chamberlain compiled logs of each of the trial pits which he dug. The log of Trial Pit 2 indicated that it was dug on 6 December 1979 to a depth of 1.3 metres, at which point, so it was recorded, “Hole stopped because clay too stiff to penetrate with hand auger”. At that point, so Mr. Chamberlain wrote in the log, the pit was, “Dry”. The other recorded observations in the trial pit were that the depth of topsoil was 0.25 metres, beneath which was “Orange clay becoming stiff brown clay”. Mr. Lord urged me to interpret the log of Trial Pit 2 dug by Mr. Chamberlain as indicating that the clay at 1.3 metres depth was dry, that is to say, desiccated, both because of the reference to the bottom of the pit being “Dry” and because, so he submitted, the fact that the soil was too stiff to penetrate indicated that it was hard, and therefore dry, clay. I accept that submission. If the soil had been stiff because it was well-hydrated the bottom of the pit would not have been dry. Mr. Robert Stokell, who appeared on behalf of the Claimants in both actions, submitted that I should treat with considerable circumspection the written records of any ground investigations not undertaken specifically in the context of the works the costs of which are claimed in these actions because one did not know anything about the skill or competence of those undertaking those investigations. That is a fair point so far as it goes, but it seems to me, given the limited information put before me and before the expert witnesses in these actions, that it would not be appropriate simply to disregard any piece of evidence which is available. Rather I should consider it along with the totality of the other evidence. Moreover, in the absence of any specific reason to doubt the skill and competence of someone undertaking soil investigations at the Site or on Plot 9 or Plot 10, it seems to me that I should proceed on the basis that whoever undertook a particular investigation was setting out to do it properly and was viewed by those who entrusted the task to him or her as apparently competent to do it.

Matthew seems to have commissioned a firm of structural engineers, Messrs. Marks, Heeley and Brothwell (“MHB”) to give advice concerning the design of the foundations for the houses to be constructed on the plots into which the Site was to be divided for the purposes of the Development. The recommendations of MHB were set out in a document dated 17 June 1980 and entitled “Bury Street Farm Ruislip Recommendations on Foundation Design”, of which a copy was put in evidence. That document included the following:-

Mr. Lord submitted that the terms of paragraphs 4.2 and 4.3 of the document from which I have quoted in the preceding paragraph were evidence that two of the trees shown on the aerial photograph taken on 18 July 1969 as standing within the boundaries of what became Plot 10 were oak trees. Mr. Stokell contested that submission, asserting that the reference in paragraph 4.2 was more, or at any rate equally, consistent with the reference being to trees in the Wood. I accept the submission of Mr. Lord on this point. It seems to me that there is a plain contrast between paragraph 4.3, which was in terms concerned with trees in the Wood, and paragraph 4.2, which was concerned with trees along the boundaries of the Site, but within those boundaries.

There was put in evidence a copy of a letter dated 19 June 1980 written by MHB to Matthew which included this reference:-

Mr. George Mist, who on the day he appeared in the witness box was to retire as the Council’s Chief Ranger after 30 years service in that role, gave evidence that before the commencement of the Development the Site was very overgrown and derelict. That evidence was not contested and I accept it. In the light of it I conclude, contrary to the submission of Mr. Stokell that there was no evidence as to when any of the trees shown on the aerial photograph taken on 18 July 1969 as then existing on what was to become Plot 9 or Plot 10 were removed, that the relevant trees were not removed until shortly before, and for the purposes of facilitating, the Development.

It was not, I think, in dispute, that, as originally constructed, the foundations of House 9 were sunk to a depth of 2.3 metres, or thereabouts, along the rear wall and for a short distance at each of the returns of the rear wall, with the remaining foundations being taken to a depth of 2 metres.

The foundations of House 10 were taken to a uniform depth of 2.3 metres.

There was put in evidence a note of an inspection made of the construction of the foundations of Plot 9 on 3 September 1980 by the Council’s building inspector. For what it is worth, which in my judgment is not much, the note recorded that it had not been possible to enter the foundation trench because it was unstable, but from ground level no tree roots had been observed within 300 millimetres of the bottom of the trench. A similar note was made in relation to the foundation trench of House 10 based on an inspection on 10 September 1980.

Mr. Siddiqui made a statement dated 24 February 2003 for the purposes of the Siddiqui Action. The accuracy of the evidence given in the statement was not contested and Mr. Siddiqui did not attend the trial to give evidence in person. His witness statement included these passages:-

There were put in evidence the logs of two trial holes dug by National House-Building Council (“NHBC”) immediately outside the footprint of House 9 on 19 November 1987. Trial hole 1 was at the rear right-hand corner of House 9, viewed from the road. It was sunk to a depth of 3.55 metres. The log recorded that fill had been found to a depth of 0.9 metres, then down to a depth of 2.56 metres the ground was described as, “Brown London Clay with grey inclusions, odd traces of sand small roots present throughout bore”. Between a depth of 3.05 metres and the bottom of the trial hole the ground was described as, “very firm brown London clay with numerous selenite crystals, clay moist with odd pieces of decayed wood”. Trial hole 2 was dug at the rear left hand corner of House 9 and was continued as a borehole to a depth of 3.55 metres. The record of what was found was, “Throughout bore was brown London clay which was moist (no signs of any roots)”.

As part of the investigations at this time Messrs. Michael Gallie & Partners (“Gallie”) were instructed to prepare a level survey of House 9. A plan showing the levels as measured was put in evidence. I shall return to the possible significance of that level survey. According to a letter dated 25 March 1988 written by Messrs. Sinclair Johnston (“Sinclairs”) to Mr. Breed of McLarens, of which a copy was put in evidence, at the time the significance of the level survey was thought to be that it showed that the rear right-hand corner of House 9 had settled relative to the rest of the house. The letter included this passage:-

Three boreholes were sunk by Anchor Foundations Ltd. (“Anchor”) on 11 May 1988 for the purpose of providing information to assist in the design of underpinning for the rear of House 9. Copies of the logs of those boreholes were put in evidence. For present purposes it is only material to record that the logs did not indicate that any roots had been found below the level of a depth of 3.2 metres in any of the locations tested. Soil samples from the boreholes were sent for testing by Eastern Soil Search Ltd. (“Eastern”). A report on those tests was given by a letter dated 8 June 1988 written by Eastern to Anchor. The only part of that report which is material for present purposes was a comment that, “A slight moisture deficiency may be present at 1.00 metres depth at Borehole 3”. The results of the ground investigation were considered in an internal memorandum written by Mr. E. S. Hunt of McLarens to Mr. Breed. The context of the consideration was whether it might be possible for Mrs. Siddiqui’s insurers to make a recovery in respect of their expenditure in underpinning the rear of House 9. The memorandum included:-

Mr. Breed of McLarens did write a letter dated 1 August 1988 to the Council. What he said was:-

The underpinning scheme adopted in 1988 for House 9 involved underpinning to a depth of 3.9 metres along the rear wall of the house, with a continuation at the returns for a short distance on the left and a rather longer distance on the right. Mr. Breed attended the site during the undertaking of the work as he was supervising it on behalf of McLarens. He was called to give evidence at the trial before me. He said that he looked into the trench in which the new foundations were to be constructed. He did not see any roots at a depth below 3.2 metres. He was satisfied that the underpinning work had been undertaken satisfactorily and the underpinning appeared to him to provide an adequate foundation. I accept that evidence.

In August 1988 three further trial pits were dug at Plot 9. Sinclairs made a note in relation to a site visit on 15 August 1988. According to that note, in Trial Pit 1 some fine roots were found at a depth of 3 metres, in Trial Pit 2 no roots were found below the level of the existing foundations, while in Trial Pit 3 some fine roots were found at an unspecified depth. The roots found were sent to the well-known testing house, Richardson’s Botanical Investigations (“Richardsons”). In a letter dated 12 September 1988 Richardsons reported:-

In a letter dated 2 April 1991 to McLarens Mr. Siddiqui reported that:-

An organisation called Engineering Services for Insurers (“ESI”) was engaged to investigate. ESI reported on the results of a visual inspection of House 9 in a letter dated 3 July 1991 to Mr. Siddiqui, of which a copy was put in evidence. The letter included:-

Mr. Siddiqui again instructed Sinclairs to advise. Site notes made by that firm on 3 October 1991 recorded the following damage:-

fine raking crack in flank wall (in cupboard over stairs)

Mr. Breed wrote to the Council about the new damage to House 9 in a letter dated 7 October 1991. That letter included:-

In a letter dated 7 October 1991 to Mr. Breed of McLarens Sinclairs expressed the initial view that, “The key movement, the subsidence and rotational movement of the front wall where it abutts [sic] the partition to the hallway measures as much as 8mm.” In the same letter the possibility of the cause of the damage then being experienced being heave was dismissed. However, in a letter dated 22 October 1991 to Mr. Breed Sinclairs expressed the view, following inspection of a trial pit, that, “the present damage is caused by an element of heave by increased volume of the clay subsoil under the main body of house.” Various further investigations were recommended, including a survey of the drains serving House 9 and the fixing of crack monitors. Of significance so far as the matters which I have to decide are concerned is that one of the further investigations recommended was the excavation of further trial pits, this time by R. M. Brown Foundations Investigations Limited (“Brown”). It does not appear that any further trial pits were in fact dug at this stage, but Brown did undertake ground investigations later, in 1998, and I shall come to the matters revealed by those investigations.

Although the Council did not reply to the letter from Mr. Breed dated 7 October 1991, it did, in January 1992 cause some trees in the Wood to be pruned. It did not do any other work on any of the trees relevant to these actions between that time and 1998.

It seems that the damage sustained by House 9 in 1991 was dealt with by repairs to the structure and decorations, with no further underground work.

Mr. Siddiqui noticed yet further damage to House 9 in about August 1997. Once more he consulted Sinclairs. They undertook an inspection of House 9 on 11 September 1997 and prepared a record of what they then found. The record was:-

Mr. J. S. Johnston of Sinclairs sent a copy of the record set out in the preceding paragraph to Mr. Breed under cover of a letter dated 19 September 1997 in which he wrote, so far as is presently material:-

Mr. Breed wrote once more to the Council on 12 January 1998. He set out the history of his principal’s dealings with Plot 9 and with the Council, and concluded:-

Investigations undertaken at Plot 9 in 1998 included the sinking of boreholes by Brown and the fixing of crack monitors by a company called Avongard Ltd. (“Avongard”). It was common ground before me that the crack monitoring showed little of value, because readings were only taken twice, on 26 February 1998 and on 21 September 1998. Although each crack monitored widened somewhat, as the monitors were placed before the annual growing season for deciduous trees in Southern England began, but at a time when, if soil was re-hydrating, one would expect that process to be active, it was impossible to draw any sensible conclusion as to the cause of the widening of the cracks monitored.

Brown sank three boreholes on Plot 9 on 26 February 1998. Boreholes 1 and 2 were each sunk from the bottom of a trial pit. Trial Pit 1 was dug at the rear right-hand corner of Garage 9, as viewed from the road. Trial Pit 2 was dug in the front right-hand corner of the dining room of House 9, that is to say, midway along the right-hand wall of House 9 as viewed from the road, but inside the footprint of the house. Logs of the boreholes were put in evidence.

The log of Trial Pit 1 showed that the pit was dug to a depth of 1850 millimetres. Roots of live appearance with a diameter of up to 7 millimetres were noted down to a depth of 1500 millimetres, with roots of live appearance with a diameter of up to 3 millimetres from that depth down to the bottom of the pit. In Borehole 1, sunk from Trial Pit 1, hair and fibrous roots were noted to a depth of 3.6 metres. The borehole was taken to a depth of 5 metres and was noted as dry at the bottom. A number of samples of roots from Trial Pit 1 were sent to Richardsons for identification and testing. In a report dated 14 March 1998 Richardsons identified one root sample as oak and as having been alive shortly before being removed from the soil. They said that the other 27 root samples appeared to be similar.

Trial Pit 2 was dug to a depth of 1.4 metres, which did not take it below foundation depth. Borehole 2 was sunk from Trial Pit 2 to a depth of 5 metres. Slight water seepage was noted at 3.4 metres depth and the borehole was noted as moist at the base. Below the level of 1.4 metres depth roots of dead appearance with a diameter of up to 2 millimetres were noted to a depth of 1.8 metres, roots of up to 1 millimetre in diameter were noted below that down to a depth of 2.5 metres, and hair and fibrous roots were noted below a depth of 2.5 metres down to a depth of 3.2 metres.

Borehole 3, in the front garden on the left-hand side viewed from the road and approximately in front of the front door, was taken to a depth of 5 metres. Hair and fibrous roots were noted to a depth of 1.7 metres. The clay between 0.7 metres and 1.5 metres was noted to be moist, as was the clay between 4.7 metres depth and the bottom of the bore. The borehole log noted that, “Slight water seepage at 4.7m below ground level. Borehole moist at base and open on completion.”

In a letter dated 21 April 1998 to McLarens Mr. Colin Chambers, the Council’s Trees and Woodlands Officer, indicated that he would cause works to be carried out to trees in the Wood on an “entirely without prejudice basis”. Those works, which were actually carried out, included removal of an oak tree which he identified on a plan of proposed works as Tree C, but which did not appear to be in the position of a tree shown on the aerial photograph taken on 18 July 1969, removing the lowest two limbs and reducing by 50% the crown of an oak tree which he identified as Tree G, which seems to be Tree 42, the removal of an oak tree which he identified as Tree H, which seems to be Tree 41, and the reduction of a hornbeam, which he identified as Tree I, but which seems to be Tree 40, so that both stems were the same height. A hornbeam which Mr. Chambers identified as Tree F and in respect of which he proposed to take no action, seems to be Tree 43. Mr. Chambers noted on his plan as Tree L what in fact was Tree 23. He recorded Tree L as privately owned.

In the event, in order to deal with the damage which manifested itself in 1997 House 9 was fully underpinned by means of a piled raft. Garage 9 was not underpinned as the expense was not considered justified by the benefits which would be derived from that course. In the context of the remedial work a level survey of both House 9 and Garage 9 was undertaken by Messrs. Gryphon Surveys (“Gryphon”), to the significance of which I shall return.

It does not appear that any structural problems with House 10 were noted until 1995. Mr. Sohanpal submitted a claim to his buildings insurers in a claim form dated 8 September 1996, of which a copy was put in evidence. The damage as described in the claim form was, “Number of major cracks have been appeared [sic] in living room, bedroom, kitchen walls and floors”. That damage was said to have occurred “Last winter” and to have been discovered “2 months ago”. In his witness statement prepared for the purposes of the Sohanpal Action Mr. Sohanpal said, at paragraph 4:-

Although McLarens were involved with the case of Mr. Sohanpal, as in the case of Mr. and Mrs. Siddiqui, as loss adjusters, this time it was a different office and the person concerned was not Mr. Breed, but Mr. Stephen Coates. He wrote a letter dated 8 February 1997 to the Council in which he said:-

Prior to devising a scheme of remedial works for House 10 instructions were given to Brown to undertake soil investigations on Plot 10. Brown dug a trial pit on 10 December 1996 which was extended by a borehole from the bottom of the pit, and sank a second borehole. The trial pit was dug at the rear left-hand corner of House 10, viewed from the road, that being the location in which the most significant cracking seemed to have occurred. The other borehole was sunk in the front garden, to the right-hand side as viewed from the road. Logs of those investigations were put in evidence. The trial pit was taken to a depth of 2.5 metres, just below the foundation level, and the log recorded various roots of live and dead appearance down to that level. In the log of the borehole from the bottom of the trial pit hair and fibrous roots were recorded down to a depth of 2.9 metres. That borehole was taken to a depth of 5 metres and was recorded as dry on completion. The second borehole log recorded occasional hair and fibrous roots only down to 0.9 metres, although it too was taken to a depth of 5 metres. At that depth it was recorded as dry. A sample of root recovered from between 1.5 metres and 2.3 metres depth in the trial pit was sent to Richardsons for identification. In a letter dated 24 December 1996 to Brown Richardsons reported that the root was oak and had been alive shortly before being dug up.

In the event the remedial scheme decided upon in the case of House 10 was also a piled raft underpinning. Invitations to contractors to tender for the necessary works were despatched, it seems from the terms of one of the tenders returned – that of Force Foundations Ltd., on or about 4 April 1997. Subsequently, in a letter dated 17 April 1997, Mr. Coates wrote again to the Council. The letter included:-

The case of Mr. and Mrs. Siddiqui in the Siddiqui Action and the case of Mr. Sohanpal in the Sohanpal Action depended, essentially, upon expert evidence to support the conclusion that the cause of the damage in respect of which a claim was made in each case was subsidence resulting from the abstraction of moisture from the soil beneath House 9, Garage 9 and House 10 by roots from oak trees in the Wood. In each case there was evidence from a structural engineer and from an arboriculturalist on behalf of the Claimants. The experts in each case were the same. The structural engineer was Mr. Andrew Marcham and the arboriculturalist was Mr. Christopher Davies. It was their evidence, really particularly that of Mr. Marcham, that the cause of the damage in each case was subsidence, and it was their evidence, really particularly that of Mr. Davies, that the cause of the subsidence was water abstraction by roots from trees in the Wood. Those conclusions depended upon the interpretation which they respectively placed upon the soil investigations to which I have already referred in the light of their expert knowledge and experience, and one or two other factors to which I shall refer.

The expert evidence called on behalf of the Council in each case was also that of a structural engineer and that of an arboriculturalist. Again in each case the same individuals were involved. Mr. Andrew Billingham was the structural engineer and Dr. Frank Hope was the arboriculturalist. A consideration of substantially the same material as led Mr. Marcham and Mr. Davies to their conclusions that the cause of the damage in each case was subsidence resulting from water abstraction from the soil by roots of trees in the Wood led Mr. Billingham and Dr. Hope to the conclusions that the cause of the damage to House 9 and House 10 was heave caused by re-hydration of the soil beneath each which was desiccated at the time of construction as a result of the removal of trees formerly on the sites of Plot 9 and Plot 10 and the action up to that point of roots from trees in the Wood which would have been severed by the construction of the foundations of House 9 and House 10. In the case of Garage 9 it was accepted that the cause of damage was subsidence, but the likely cause was the action of vegetation in the garden of Plot 9 adjacent to Garage 9.

Both Mr. Marcham and Mr. Billingham were first involved with Plot 9 and Plot 10 after the completion of the remedial work which forms the principal subject matter of the claim in each case. Each was therefore entirely dependent upon his interpretation of the records of damage and investigations made by others in reaching his conclusions. Indeed the report of each of Mr. Marcham and Mr. Billingham in each of the actions was very largely a recital of, and a commentary upon, such records.

Dr. Hope was in the same position as Mr. Marcham and Mr. Billingham in not having been involved in either case until after the litigation had been commenced. Mr. Davies, on the other hand, had actually been instructed in relation to Plot 9 in 1998 and had prepared a report dated 6 February 1999 which was put in evidence.

In considering the expert evidence in the Siddiqui Action it is convenient to begin with that of the arboriculturalists. Mr. Davies and Dr. Hope plainly put much effort into a consideration of what they could agree, to great benefit, and recorded what they did agree in a document which was put before me. That document included the following:-

The effect of Mr. Davies’s evidence on matters not agreed in the Siddiqui Action can be summarised quite simply. It is notorious that oak trees are a major cause of subsidence. The area of influence, that is to say, the radius within which the roots may be expected to affect the moisture content of the soil, of oak trees can be up to 35 metres. House 9 and Garage 9 are within 35 metres of where there were, until they were cut down, oak trees in the Wood. Therefore the cause of any subsidence of the soil beneath House 9 or Garage 9 was oak trees in the Wood. In his report in the Siddiqui Action at paragraph 1.1.3 Mr. Davies put his view in this way:-

In his first report for the purposes of the Siddiqui Action Dr. Hope included an illuminating section concerning the significance of the finding of decayed wood in ground investigations on Plot 9. It is worth quoting the section substantially in full.

Another section of Dr. Hope’s first report in the Siddiqui Action which I have found of considerable assistance was section 17, in which he considered specifically the issue whether roots of trees in the Wood would have affected the moisture content of the soil beneath the footprint of House 9 after the underpinning of the rear foundations. I accept what he wrote in that section, which was:-

While, at some points in his evidence, Dr. Hope envisaged the possibility that the cause of the damage to House 9 was subsidence, I am satisfied that that is not so. The evidence of Dr. Hope concerning the actions and activities of the roots of oak trees is one of the factors which has led me to my conclusion, because if, as I do, I accept the evidence of Dr. Hope that the roots of trees from the Wood could not have caused moisture to be abstracted from the soil under the footprint of House 9 at the time of the damage in 1997, what other cause of moisture abstraction could there be which could have caused that damage? In my judgment the answer is none. It seems to me that at the time of construction of House 9 conditions were ripe on Plot 9 for the occurrence of heave. Tree 39 was not, perhaps, particularly large, but it was right on the footprint of House 9 and, on my findings, was removed only shortly before House 9 was built. Until removal Tree 39 must have drawn moisture from the soil on which it stood and there created at least a local moisture deficiency to whatever depth its roots went and however widely they spread. Until House 9 was built there was no obstacle to the spread of roots from trees in the Wood, in particular the large trees Tree 41, Tree 42 and Tree 43, into the area which became Plot 9. On the evidence of Dr. Hope, which I accept, the roots which so spread are likely to have spread at a depth of between 1 and 2 metres below ground level. There was no reason for them to go any deeper. However, at between 1 and 2 metres depth they would have been abstracting moisture at a depth which would not have been re-hydrated by seasonal rainfall, so there would have been desiccation. The roots, on the evidence of the ground investigations to which I have referred, may have gone as deep as 3.2 metres below ground level. I accept the evidence of Dr. Hope that the discovery of dead roots beneath, and decaying wood adjacent to, House 9 indicate that there had formerly been vegetation on the footprint of House 9, the removal of which would have been conducive to heave. The ground investigations to which I have referred did not at any stage reveal clear evidence of desiccation, which would be necessary if the mechanism of damage was to be subsidence, after House 9 was built. The results of Mr. Chamberlain’s digging of his Trial Pit 2, however, provide clear evidence that ground in the vicinity was desiccated at a depth of 1.3 metres in December 1979, which was outside the growing season and at a time of year when re-hydration would usually be expected to be taking place. Such desiccation would be a necessary precondition to heave. As I have pointed out, the slight evidence of desiccation found in the 1988 investigation of the soil at Plot 9 is logically consistent with a soil which has been desiccated and is re-hydrating not yet having achieved equilibrium. On the other hand, there was fairly clear evidence of moisture at depth in some soil investigations which ruled out subsidence at the points sampled, but was consistent with heave. There was also evidence, which I shall explain in more detail a little later, that a comparison of the levels of House 9 as surveyed by Gallie and by Gryphon showed that, with the exception of the rear right-hand corner, the level of House 9 had risen between the Gallie survey and the Gryphon survey. I accept that evidence. Looking at the totality of the evidence, in the light of the expert evidence as to the indicia of heave and of subsidence, respectively, I am satisfied that what House 9 suffered from in 1997 was heave. If necessary, I should have found that that was the cause of all the problems going right back to 1988. It would certainly have explained both why the partial underpinning solution adopted in 1988 was unsuccessful and why Mr. Siddiqui noticed the recurrence of damage within weeks of the completion of the underpinning works.

Mr. Marcham’s opinion that the cause of the damage to House 9 was subsidence was, as was clear from his report dated 26 February 2003 in the Siddiqui Action, the result of a process of elimination. He was satisfied that the cause was not heave, therefore it had to be subsidence. An illustration of his approach was what he said about the damage to House 9 with particular reference to that in 1987, which he called “Phase 1 damage”, in paragraph 8.6 of his report:-

As I have already recorded, it proved to be common ground that the cause of damage to Garage 9 in 1997 was subsidence. That was not suggested to be inconsistent on technical grounds with the contention that the cause of the damage to House 9 was heave, and was not inconsistent, in my judgment. There was no reason why different parts of Plot 9 should not be subject to countervailing movements of the soil at the same time. The question then is what was the cause of the subsidence in the soil under Garage 9? In the light of the matters agreed between Mr. Davies and Dr. Hope, which I accept on this point, one cannot say. Dr. Hope was pressed in cross-examination on the issue and he said his prime candidate for causing the damage would be the Lawson’s Cypress tree 2 metres away from the corner of Garage 9 which had suffered damage. If compelled to make a finding, I should accept that evidence of Dr. Hope, by whose evidence, as I have said, I was very impressed. However, it is enough for present purposes that I should accept what Dr. Hope and Mr. Davies agreed about it for the claim in relation to Garage 9 to fail for want of proof.

At paragraph 8.2 of his report in the Siddiqui Action Mr. Marcham gave evidence, which was not contested, that periods of severe drought since the Second World War have been 1947, 1975 – 1976, 1989 – 1992 and 1995. On the evidence in the Sohanpal Action House 10 sustained no damage as a result of the extended period of severe drought between 1989 and 1992, which fact was urged upon me by Mr. Lord, convincingly as it seemed to me, as an indication that whatever was the cause of the damage to House 10 in 1995 it was not subsidence. The point was reinforced, submitted Mr. Lord, by the fact that, according to Mr. Sohanpal’s insurance claim form, which I have already indicated I accept as accurate in this regard, damage to House 10 first occurred during the winter, which is not the growing season for deciduous trees in Southern England.

Mr. Lord relied heavily, in support of the Council’s case that the cause of the damage to House 10 in 1995 was heave, upon the presence, location, number and size of the trees present upon the site of what became Plot 10 before the construction of House 10, specifically Tree 38, right on the right hand rear corner where the worst damage to House 10 occurred, Tree 36 just outside the footprint of House 10 on the rear left corner, Tree 37 in the rear garden, and Trees 34 and 35 in the front garden. Not to be overlooked, submitted Mr. Lord, was Tree 23 in the curtilage of the Public House, which was still there. All of these were very telling points. While it was correct that Garage 10, immediately beneath Tree 23 had not suffered damage, Mr. Lord submitted that that was probably because the foundations of that building would have been relatively shallow. That may be, but there was in fact no evidence as to the depth of the foundations of Garage 10.

Mr. Davies and Dr. Hope reached agreement as to a number of matters for the purposes of the Sohanpal Action and set those matters out in a document which was put before me. What was agreed included:-

Mr. Davies sought, shortly before the start of the trial, to go back upon what he had agreed with Dr. Hope as set out in the preceding paragraph. Unhappily that effort did him no credit. He sought to say that at the time he made his agreements with Dr. Hope he was under a misapprehension as to where the principal damage in House 10 had been. That was demonstrated to be untrue by a reference in his report in relation to the Sohanpal Action at paragraph A to having been provided prior to his meeting with Dr. Hope with a copy of a report of Mr. Marcham dated 9 November 2001. Consideration of that report showed that the description of the damage to House 10 given was consistent with the evidence as to the location of the principal damage given to me. Mr. Davies did not provide a convincing explanation as to how, in those circumstances, he came to make his alleged mistake, and I am satisfied that he did not make a mistake. To put it colloquially, once it was appreciated that the effect of the matters which he had agreed with Dr. Hope made the claim in the Sohanpal Action all but unsustainable, he was “nobbled” to change his evidence. I am satisfied that the agreements which he originally made were proper agreements for him to have made and that they do have the feared consequence of dooming the claim in the Sohanpal Action. Mr. Davies’s attempt to identify the Council’s trees as responsible for the damage to House 10 in his report dated 26 February 2003 prepared for the purposes of the Sohanpal Action on its face lacked all conviction, as it seemed to me. The relevant passages were:-

In his first report prepared for the purposes of the Sohanpal Action Dr. Hope said in paragraph 18.5, in a passage which I accept as accurate:-

Mr. Marcham expressed the view in paragraph 7.1 of his report prepared for the purposes of the Sohanpal Action that:-

The other particular point upon which Mr. Billingham relied in support of his view that the cause of damage to House 10 was heave was what he contended was clear evidence that the front porch slab at House 10 had risen. Mr. Marcham, with the greatest reluctance, as it seemed to me, at length accepted that the evidence did indeed indicate that the front porch slab at House 10 had risen as a result of heave. However, he then sought to persuade me that that circumstance told one nothing about the cause of the damage to the main part of House 10. He told me that the foundations of the porch might be very shallow, which seemed to be pure speculation on his part. What he would have me believe, as it appeared to me, was that the soil might be subject to heave on the outside of the front door, as it were, whilst being subject to subsidence on the inside of the front door. Whilst I recognise that different parts of a plot of land may contemporaneously be subject to subsidence and heave, it does not seem particularly likely that these different effects should be observed dramatically within a distance of a couple of feet. In the end I concluded that Mr. Marcham was simply trying to marginalise a piece of evidence which was inconvenient to the position which he had adopted.

I reject the evidence of Mr. Marcham also in relation to the cause of the damage to House 10. I find that the cause of the damage sustained in 1995 was heave. Consequently the claim in the Sohanpal Action also fails.

In the light of my conclusions as to the nature and cause of the damage in each of the Siddiqui Action and the Sohanpal Action, it is not strictly necessary to consider the other lines of defence advanced on behalf of the Council. However, as I have heard all of the relevant evidence and argument, it is convenient that I should indicate my conclusions on those issues.

It was, I think, common ground that the approach which I should adopt to the questions of reasonable foreseeability and abatement was that indicated by the House of Lords in Delaware Mansions Ltd. v. Westminster City Council[2002] 1 AC 321. The only substantive speech in that case was that of Lord Cooke of Thorndon. At pages 332 to 334 of the report Lord Cooke said this, so far as is presently material:-

The question what was involved in giving a tree owner a reasonable opportunity to abate a nuisance caused by tree roots was considered by the Court of Appeal in L. E. Jones (Insurance Brokers) Ltd. v. Portsmouth City Council[2002] EWCA Civ 1723. The only substantive judgment was that of Dyson LJ. At paragraph 22 of his judgment he said:-

In the Siddiqui Action Mr. Lord submitted, first, that bearing in mind the date of the construction of House 9 and the fact that it was constructed apparently in compliance with the guidelines as to foundation construction of NHBC, the Council had no reason reasonably to foresee the risk of any damage to the structure of House 9 from the roots of trees in the Wood until such damage in fact occurred, assuming, contrary to my findings, that such was the occasion of damage to House 9. I accept that submission. Modern standards of construction can be expected to take account of obvious hazards in the vicinity of the structure to be built, as the trees in the Wood were in relation to any structure to be constructed on Plot 9.

Then Mr. Lord submitted that, after the first occurrence of damage to House 9, the Council had no reason reasonably to foresee the risk of a recurrence of damage, bearing in mind that the objective of the underpinning works undertaken at that time was to eliminate such risk. That submission seems to conflate two separate issues. The first of those issues is what was it, after the first occurrence of damage, that the Council knew about what had happened. The second is what assumptions, in the light of that knowledge, the Council was entitled to make about the risks for the future. The effect of the decision of the House of Lords in Delaware Mansions Ltd. v. Westminster City Council, so far as is presently material, it seems to me, is that the Council should be taken to have foreseen what it did actually foresee, or what it ought to have foreseen as a reasonable landowner. There was no evidence before me of any actual consideration on the part of the Council of any risk of damage to House 9. The only material from which I can draw any inferences is the evidence as to what the Council did, or caused to be done, in relation to the trees in the Wood in 1992 and 1998. However, it is plain that the Council was put on notice by Mr. Breed’s letter of 1 August 1988 of the occurrence of damage to House 9, and the receipt of such notice should have put the Council, as a reasonable landowner, on notice of the risk of further damage to House 9 unless some appropriate steps were taken. The same letter indicated that remedial works were intended, but not what. It seems to me that the Council was not entitled to make any assumptions as to the likely or intended effect of such works in relation to the risk which had by then, on the hypothesis which must be adopted in relation to my consideration of the issues in this part of this judgment, eventuated. The Council, in my judgment, is not entitled to rely upon what it would have discovered if it had enquired as to the nature of the works undertaken in 1988 as negativing foreseeability as it made no enquiries at the time and placed no reliance upon what it might have learned, but did not.

Quite apart from the point considered at the end of the preceding paragraph, by Mr. Breed’s letter dated 7 October 1991 the Council was again put on notice of the occurrence of damage to House 9. Whatever assumptions it might have been entitled to make up to that point about the risk of damage from trees in the Wood, from that time forward, on the hypothesis adopted, it was reasonably foreseeable that the trees could cause damage. The Council at that stage plainly recognised the risk and took steps to reduce or avoid it, namely by pruning trees in the Wood. However, it took no steps to put in place, or to maintain, any regime of continued management of trees which could affect House 9. No further work was done until 1998, after yet a further instance of damage. In all the circumstances, had it been necessary to do so, I should have held that damage to House 9 from trees in the Wood was reasonably foreseeable by the Council from the date of receipt of Mr. Breed’s letter dated 1 August 1988, or at the latest, from the date of receipt of his letter dated 7 October 1991.

Mr. Lord submitted that the damage which occurred to House 10 in 1995 was not reasonably foreseeable because the Council was entitled to make the same initial assumption in relation to its standards of construction as in relation to House 9 and no damage had occurred until that complained of in the Sohanpal Action. If the circumstances in relation to House 10 were all that fell to be considered, I should have accepted the submission of Mr. Lord. However, in my judgment the question of whether damage to a structure is reasonably foreseeable falls to be determined not in a vacuum, but in the light of what a reasonable landowner knew or ought to know about adjacent properties and on the basis of which he ought to make his assessment of the risk to the structure in question. In other words, in the light of what, by 1995, the Council knew about the damage to House 9, it was reasonably foreseeable that there was a risk to House 10. Any assumption which it might have been reasonable to make about the adequacy of the foundations of House 10 was undermined by the occurrence of damage to House 9 which was constructed by the same builder at the same time as part of the same development. If the foundations of one house were inadequate to resist the action of tree roots, so might be the foundations of the house next door.

While Lord Cooke in Delaware Mansions Ltd. v. Westminster City Council considered the questions of giving notice of damage to a tree owner and an opportunity to him to abate the nuisance by removal of the tree which has caused the damage, it is wrong, in my judgment, to treat those matters as conditions precedent to recovery of damages in a case of damage caused by tree root incursion, such that, absent notice and the affording of an opportunity to remove, no recovery is possible. Although Lord Cooke did not himself articulate it, in my judgment it is implicit in his consideration of the points as to notice and opportunity to do works to the offending tree that in the circumstances of the particular case if the tree is removed the remedial works proposed will either be rendered unnecessary or can be less extensive. That was the situation in Delaware Mansions Ltd. v. Westminster City Council itself. In a case in which it makes no difference to the required works nothing is achieved by giving notice and an opportunity to remove the guilty tree. Thus it is, it seems to me, for him who contends that the remedial works would either have been unnecessary or less extensive had the relevant tree been removed to demonstrate that by evidence. Unless he does so, the questions of whether notice of intended works and an opportunity to remove the offending tree have been given do not sensibly arise. In the Siddiqui Action there was no evidence that the works in fact undertaken in 1999 would have been unnecessary or less extensive if some tree or trees in the Wood had been removed. As some trees were removed and others reduced in 1998, yet still the works the cost of which was claimed were undertaken, the only sensible conclusion is that the removal of trees and reduction of trees had no impact upon the necessary works. Thus this line of defence would have failed, had it been necessary to rely upon it. In any event it seems to me that by his letter dated 12 January 1998 Mr. Breed gave ample notice and opportunity to the Council to seek to avoid the need for remedial works as extensive as were in fact undertaken by works to the trees in the Wood, if that was what the Council wanted to do.

There was no evidence in this action either that the need for works as extensive as those in fact undertaken to House 10 could have been avoided by some works to the trees in the Wood. For that reason the defence based upon loss of any opportunity of abatement would have failed in this action also. Had it been necessary to do so, however, I should also have held that Mr. Coates’s letter dated 17 April 1997 did afford the Council an adequate opportunity to suggest the undertaking of works to the trees in the Wood as an alternative to the undertaking of works to House 10, had it wished to do so.

For the reasons which I have given in relation to the Siddiqui Action the claims in that action fail and that action is dismissed.

For the reasons which I have given in relation to the Sohanpal Action the claims in that action also fail and that action is also dismissed.