England and Wales High Court (Technology and Construction Court) Decisions

IN THE HIGH COURT OF JUSTICE
QUEEN'S BENCH DIVISION
TECHNOLOGY AND CONSTRUCTION COURT

		Royal Courts of Justice Strand, London, WC2A 2LL
		25th May 2011

 


JUDGE WILCOX :

Introduction

1. This is a tree root subsidence case. The Claimant is and was at all material times the freehold owner of 18 Highbury, New Park, London, which is in the borough of Islington (Second Defendant). It is converted into eight flats, and Mrs Berent lives in Flat 18a.
2. Next door at No. 20 is the building owned by the First Defendant housing association (Mosaic). The street in which these buildings stand comprises large Victorian houses in treed gardens. The pavements are lined with mature London plane trees.
3. No.18 is an impressive town house constructed between 1850/70. There is a medium sized walled garden to the front of the property and a large garden at the back bordering on to a deep railway cutting. To the rear of this railway cutting and below run two tunnels, the up and down Channel Tunnel railway lines going into and from St Pancras. These were constructed in September and October of 2003.
4. Viewed from the road the main body of the building is four storey, including a basement level. There is a large stone porch with a portico to the front incorporating a flight of steps up to the elevated ground floor.
5. To the left and closest to Mosaic's property at No.20 is a part two storey, part single storey flat roofed wing added to the main body of the building. To the right is a three storey wing housing a garage at front ground floor level with residential accommodation above. Both of these wings are flat roofed and appear roughly contemporaneous with the main body of the house.
6. The left wing accommodates the flat of Mrs Berent, the owner. Her bathroom is supported by an arch into the dividing wall between Nos.18/20 with a passage running underneath it.
7. The land on which No.18 is built slopes from right to left. That part of the garden of No. 20 adjacent to No. 18 is several metres below that of No. 18 and the boundary wall serves as a retaining wall to the raised level of No. 18. No. 20 also has a garage abutting No. 18, and the extension of the front dividing wall as it goes away from the front garden forms part of the garage wall of No. 20.
8. The land on which No. 18 stands, not only slopes from right to left viewed from the road, but also slopes quite steeply to the rear, to the railway cutting.

The Trees Relevant to the Claim

9. The Second Defendant is responsible for two mature London plane trees in the pavement at the front of No. 18. T2 to the front left approximately 12 metres from the front elevation and in 2008 approximately 10 metres high. T3 to the front right approximately 12 metres from the front elevation and approximately 15 metres high in 2008.
10. The First Defendant has a mature London plane T1 in its front garden recorded as 12.2 metres from the property at No. 18, and approximately 17 metres high in 2008. This tree is also described as T4.
11. The Claimant had a mature Tree of Heaven in her front garden until August 2005 five metres from the front porticos elevation and approximately 10 metres high in 2005.
12. In May 2004 there is recorded to have been a second Tree of Heaven eight metres from the front left of the house. This may have been the stump of a tree that blew down in the gales of 1987.
13. In the rear garden of No. 18 is a mature false acacia tree and an elder tree. In May 2004 there was recorded to have also been a mature bay tree five metres from the rear elevation of the house, an Indian Bean tree 15 metres from the rear and a black locust tree 22 metres from the rear.

The Structure of the House

14. The centre four storey part and adjoining left and right wings are built from traditional masonry and timber. There is a pitched roof over the central portion, flat roofs to the wings. The left wing has the flying bathroom over the passageway.
15. The building has shallow "foundations" at the left rear approximately 6cms in depth. The property sits in deep made ground, mainly of clay but containing also silt, sand, ash and bricks, to a depth of between 2.1m and 2.4m below ground level at the front and between 2.5m and 2.8m at the rear overlying The London clay.
16. At the front of the property the original foundations were proved at 2.4m below ground level coinciding with the base of the London clay.
17. The made ground is significantly more permeable than the London clay and with substantial granular content at shallow depths. Those parts of the building founded on made ground rather than natural clay are more susceptible of ground movement due to water ingress.

Drainage

18. The report of Bowbuild of 24 November 2003 was not made available but clearly further investigation was envisaged after that site visit to examine the drains.
19. On 24 November 2004 it was noted that the whole of the combined foul and storm drain system was badly blocked in 2003. Subsequently both CCTV and other integrity testing was carried out.
20. In relation to the front of the building and the left hand side extension significant leaking was found from the gully near to monitoring point 18007, to manhole 4 underneath the left hand extension necessitating excavation and renewal of the pipework. Two runs from WC1 and WC2 respectively, to manhole 4 were found to be leaking and needed excavation and replacement. The run from manhole 4 to manhole 5 was found to be cracked and relining was needed to make it watertight. The waste system from the basement kitchen was to be bypassed and replaced with another stack in the basement utility room. From manhole five at the front left hand corner of the main building to manhole six at the right hand corner excavation and complete renewal of piping was recommended. The relining of some lengths was necessary and the waterproofing of the rainwater gully because of the joint displacement between plastic and clay. This part of the leaking drainage system underlies the left hand wing and passes along the line of the front foundations and under the steps. The flow is from back to front. It is evident that both foul and storm water would escape from the drains and leech into the made up soil underneath both the basement slab and foundations and because of the fall of the drain system, beneath the front foundations.
21. Clearly the damaged drainage gave rise to significant leakages during 2003 and 2004 which were likely to have affected the weight bearing capacity of the underlying made up soil above the London clay. Following repair at the end of 2005 the drains had clearly ceased to have any deleterious effect upon the made up soil.
22. In August 2005 the remaining Tree of heaven was removed from the Claimant's front garden.

The Internal State of the House

23. In July 2004 Cunningham Lindsey, the Claimant's loss adjusters, in an Engineering appraisal report described the damage in the following terms:-

"The principal damage takes the form of cracks in external and internal walls.

The indicated mechanism of movement is a drop in level of the front elevation.

The damage will be placed in category 3 of the BRE Digest 251 classification ie moderate".

24. In April 2009 Cunningham Lindsey reported the damage as being widespread to the left and right wings of the building.
25. That on the left had rotated away from the main four storey part of the house and cracks of approximately 10mm were apparent throughout, some so serious as to warrant temporary strapping work particularly in the 'flying' bathroom, where doubts were entertained as to the integrity of the infill wall.
26. The right hand wing had rotated away from the main part of the house leading to cracking along the plane between the two.
27. The step construction leading to the basement and up to the elevated ground floor, part of the portico entrance had rotated away from the main section of the house and 15mm cracking was caused within the entrance lobby and basement flat by reason of the distortion of the portico construction.
28. An insurance claim had been made in 1999 and the portico was underpinned.
29. The removal of the Tree of Heaven nearest to the house was to be undertaken in relation to these remedial works and within the house, according to Mrs Berent who was an accurate and reliable witness, works were undertaken to put it into good and safe order. By August 2003 it was in an excellent cosmetic state with no signs of damage.
30. The portico was underpinned but the Tree of Heaven was not removed until August 2005.

The Claim

31. The claim is pleaded in both nuisance and negligence claiming that the Defendants wrongfully caused or permitted the roots of their trees to encroach on the Claimant's premises and/or extend under the Claimant's premises from about the summer of 2003 and thereafter continuing on a daily basis whereby the foundations of the house were undermined and moisture was withdrawn from the soil and the foundations, causing progressive subsistence.
32. The Claimant relies upon a common duty of care to take such steps as may be necessary to minimise or prevent damage as might occur to premises by reason of the trees being in such close proximity to the Claimant's house, such steps including pollarding, crown reduction, or such management as would prevent encroachment or damage.
33. It is contended that the risk of damage to the premises was reasonably foreseeable by reason of the Defendants' knowledge of the geology and make up of the area in which the trees were situated and that clay based soils are susceptible to shrinkage and swelling on changes in moisture content caused by tree root extraction of moisture, and desiccation. In consequence of the subsequent damage, the Claimant seeks damages for distress and inconvenience and for the costs of repair, and injunctions requiring the removal of the offending trees.
34. The First Defendant admits that the front and left hand side of No. 18 suffered from subsidence caused by a London plane from about 2005 but does not admit that its London plane tree in the garden of No.20 (T1) caused or materially contributed to the subsidence and denies that T1 caused or constituted an actionable nuisance or was injurious to the premises.
35. The First Defendant contends that the damage was caused or materially contributed to by the Channel Tunnel tunnelling works carried out in September and October of 2003 and/or by the combination of the composition of the infill ground beneath the house and affected drains leading to repair in 2005.
36. Alternatively the First Defendant relies upon the Second Defendant's nuisance or negligence in relation to its street trees T2/T3 and the Second Defendant's Tree Preservation Order covering T1 and its refusal to permit its removal.
37. The Second Defendant denies responsibility for any subsidence damage, contending that the tunnelling operations in September 2003 was the cause, and denies root encroachment and moisture extraction, and in any event denies that the load bearing capacity of the soil was affected causing removal of support.
38. The Second Defendant contends that there was no foreseeable risk of damage by its trees relying upon its regime of regular maintenance and prudent management by pruning and crown reduction and contending that it was not foreseeable that damage would occur:-

"Properties do not necessarily subside only because roots extend beneath them. Whether a property is susceptible to subsidence by action of trees is dependent upon many factors including the type of tree, the size and age of the tree, the distance of the tree from the property, when the property was built, the type of soil, the historical rainfall, the prevalent temperatures, whether there is neighbouring vegetation, the depth of the foundations and whether any other works such as underpinning have been done. These cannot always be known, so it is very difficult to predict when subsidence will or may occur."

The Law

39. In Delaware Mansions v Westminster City Council [2002] 1AC 321 (HL) Lord Cooke of Thorndon affirmed that in tree root cases, the question is still whether the Defendant has acted reasonably:-

"The label nuisance or negligence is treated as of no real significance. In this field, I think, the concern of the common law lies in working out the fair and just content and incidents of a neighbour's duty rather than affixing a label and inferring the extent of the duty from it."

40. The Claimant brings a case in nuisance and negligence. The Claimant must prove that a duty was owed and that it was breached. In Solloway v Hampshire County Council [1981] WLR 1 Dunne LJ at page 3 said:-

"The duty in respect of the nuisance arises if the encroachment of the roots is known, or ought to be known, to the owner, occupier or other person responsible for the tree and its maintenance, if the encroachment is such as to give rise to a reasonably foreseeable risk that such encroachment will cause damage."

41. In Paterson v Humberside County Council [1996] 12 Const. LJ page 64 at page 70 Mr Roger Toulson (as he then was) said that the tests of foreseeability was whether the risk was one which a reasonable person in the Defendant's position would have regarded as a real risk as distinct from a risk which he would have been justified in disregarding and taking no steps to eliminate (emphasis given).
42. Lord Cooke in Delaware at paragraph 30 of his speech went on to consider what is "reasonable":-

"30. Once more, in Goldman v Hargrave [1967] 1AC 645, the Privy Council per Lord Wilberforce, as to an occupiers duty to take reasonable steps to prevent the spreading of a fire caused by lightning striking a tree, said, at page 663, and likewise not discriminating between nuisance and negligence ...

"So far it has been possible to consider the existence of a duty, in general terms. But the matter cannot be left there without some definition of the scope of his duty. How far does it go? What is the standard of the effort required? What is the position as regards expenditure? It is not enough to say merely that these must be "reasonable", since what is reasonable to one man may be very unreasonable, and indeed ruinous, to another: the law must take account of the fact that the occupier on whom the duty is placed has ex hypothesis, had this hazard thrust upon him through no seeking or fault of his own. His interest in his resources, whether physical or material, may be of a very modest character either in relation to the magnitude of the hazard, or as compared with those of his threatened neighbour. The rule which required of him in such unsought circumstances in his neighbour's interest a physical effort of which he is not capable, or an excessive expenditure of money, would be unenforceable or unjust. One might say in general terms that the existence of a duty must be based upon the knowledge of the hazard, ability to foresee the consequences of not taking or removing it, and the ability to abate it. And in many cases, as for example in Scrutton LJ's hypothetical case of stamping out a fire, or the present case, where the hazard could have been removed with little effort and no expenditure, no problem arises but other cases may not be so simple. In such circumstances the standard ought to be to require of the occupier what is reasonable to expect of him in his individual circumstances. Thus, less must be expected of the infirm than of the able bodied: the owner of a small property where a hazard arises which threatens a neighbour with substantial interest should not have to do so much of one with larger interests of his own at stake and greater resources to protect them: if the small owner does what he can and promptly calls upon his neighbour to provide additional resources, he may be held to have done his duty: he should not be liable unless it is clearly proved that he could and reasonably in his individual circumstance should, have done more. This approach to a difficult matter is in fact that which the courts in their more recent decisions have taken".

(Emphasis added).

43. In Kirk v London Borough of Brent [2005] EWCA Civ 1701 C of A Pill LJ at para 37 said:-

"I do not accept the proposition ... that as a matter of law, where nuisance is created by tree roots there is no liability for resulting damage unless and until damage has been notified to the tortfeasor".

44. The First Defendant's tree T1 was subject to a Tree Preservation Order made in July 2007 by the Second Defendant. The consent of the Second Defendant was necessary to remove the tree by virtue of Section 211 Town and Country Planning Act 1990.
45. That consent was not given until shortly before trial. The existence of such an order, and the provisions of Section 198(6) Town and Country Planning Act 1990 are relevant elements as to the position of the First Defendant in relation to matters of abatement.
46. Section 198(6) of the 1990 Act is in these terms:-

"Without prejudice to any other exemptions for which provision may be made by a tree preservation order, no such order shall apply –

(a) to the cutting down, uprooting, topping or lopping of trees which are dying or dead or have been found dangerous, or

(b) the cutting down, uprooting, topping or lopping of any trees in compliance with any obligations imposed by or under an Act of Parliament or so far as may be necessary for the prevention or abatement of a nuisance."

47. The construction of this sub section, and the words emphasised and its effect were considered by the Court of Appeal in Perrin v Northampton Borough Council [2008] 1WLR 137. At para 7 Chadwick LJ observed:-

"Commonsense suggests that the task in such cases should be to identify and evaluate the various possible means of abating or preventing the nuisance – whether by doing something to the tree itself or by other works – and then to ask, in the light of that evaluation, whether it is, indeed, necessary to do something to the tree, and (if so) what."

48. At paragraph 56 he went on to say:-

"The better view, as it seems to me, is that Parliament intended that Section 198(6)(b) should be interpreted in a manner which gave proper weight to the word "necessary". It is intended that a protected tree should remain protected unless there was a real need to lift that protection. Effect is given to that intention by reading the expression "so far as may be necessary for the prevention or abatement of a nuisance" as "if and so far as may be necessary for the prevention or abatement of a nuisance".

49. A great deal of time at trial was occupied by parties seeking to demonstrate what were the sole or dominant causes of damage to the Claimant's property.
50. In Loftus-Brighan v London Borough of Ealing [2003] EWCA Civ Chadwick LJ confirmed that the test is whether the trees were an effective and substantial cause of the recent damage.
51. It is clear that they need not be the sole cause.
52. The first issue I must decide is what caused the extensive damage to No. 18 in September 2003.
53. It was clearly sudden as is evidenced by the account given by Mrs Berent and the inferences from the CTRL survey and monitoring evidence in relation to the tunnelling operation.
54. The Claimant's case as to causation is supported by the evidence of Mr Allen, their engineering expert, that tree induced subsidence made a material contribution to the subsidence of No. 18 from 2003. Mr Crowley, on behalf of the Claimant, relied upon four factors he identified as demonstrating this.
55. First the monitoring results provided by CTRL during the boring of the second tunnel in October 2003; second the fact that 2003 was an event year, that is a year of exceptional dryness giving rise to many claims; third the crack closure recorded in February 2004 and lastly the level monitoring results from 2004 onwards.
56. The Defendants' case supported by Mr Ainsworth, the Defendants' engineering expert, is that the damage was in fact related directly or indirectly to the tunnelling operations in September and October 2003.
57. Directly by subsidence caused by damaged drains giving rise to water leakage and/or tunnelling vibration damage to both the foundations and drains. Mr Ainsworth relies upon the absence of evidence as to true root induced subsidence, the house being in immaculate condition and damage occurring suddenly and extensively to the rear, left, right and front of the house at the same time.
58. The rear and right hand damage it is accepted by the Claimant was not related to tree root induced subsidence but to drains and tunnelling.
59. The engineering experts agree that the level monitoring results are the most useful information to establish the causes of damage to the property.
60. Crack monitoring commenced on 13 June 2004 and continued intermittently until 24 February 2008. There are large gaps between readings and none at all taken during 2006.
61. Vertical or level monitoring was undertaken from 15 June 2005 to 9 August 2007. Again this was intermittent and not wholly satisfactory.
62. Detailed level monitoring had been undertaken following the excavation of the down line Channel Tunnel link on 19 and 20 October 2003 by CTRL.
63. There was no level monitoring following the earlier excavation of the up line. The survey in October 2003 on behalf of CTRL recorded "noticeable and extensive damage particularly to the front elevation around the position at the open porch".
64. The experts agree that the monitoring to the right hand side of the property shows evidence of movement in 2003 with movement slowing in 2005 and no evidence of seasonal movement.
65. They agreed that the movement was initially caused by the tunnelling work with the continuing movement being related to the failed drainage system which may have been damaged by the tunnelling work. No evidence of tree related seasonal movement was noted to this part of the property.
66. As to the rear of the property the movement was agreed to be similar to that on the right hand side. Any slight seasonal movements recorded were within the tolerance of the levels of monitoring and in any event could have been caused by the vegetation at the rear and not by the trees to the front and to the left of the property, that is the Defendants' trees.
67. As to the movement to the front and left hand side of the property which occurred in 2003 the experts do not agree.
68. They identify possibilities, namely the tunnelling work, the failed drainage system, the desiccation of the highly shrinkable subsoil by the roots of adjacent trees, or the combination of one or more of these causes.
69. Mr Allen, the Claimant's expert, is of the opinion that the damage to the property in 2003 was caused by the seasonal drying out, and rehydration, giving rise to heave and subsidence following the very dry weather pattern of 2003. His conclusion is that trees T1, T2 and T3 caused the desiccation of the shrinkable clay sub soils and was thus an effective and substantial cause of the damage to the front and left hand side of the property during 2003 and during the monitoring period that followed.
70. The Defendants' Mr Ainsworth is of the opinion is that there is no evidence to suggest that the vegetation caused this damage in 2003. The first cyclic behaviour detected, evidencing the effects of vegetation not being evident until later in 2005.
71. The experts agreed that post June 2005 after the completion of the tunnelling work and repair of the drains the vertical monitoring results show the characteristic seasonal movement following desiccation of the highly shrinkable clay sub soil by the roots of the adjacent trees T1, T2 and T2 and rehydration. Mr Allen placed great reliance upon the CTRL data in his original report to support his contention that tunnelling was not a material and substantial cause of the damage. The monitoring data shows that the actual settlement following the boring of the second tunnel was in line with the predicted settlement by CTRL. This is 1.8mm at the front and 7.8mm at the rear giving a differential settlement of the order of 6mm insufficient in his view to cause damage to the front of the property.
72. From this he draws the inference that the settlement from the first tunnel boring must have been the same.
73. During the first boring it is known that the tunnelling machine broke down in the vicinity of No. 18 and that for some days its engines were left running.
74. During this time Mrs Berent's tenant at the rear of the property complained of vibration such that she was kept awake all night.
75. If the settlement from the first tunnel was the same as that from the second, a cause other than the tunnelling induced subsidence must have caused the sudden 2003 damage to No. 18.
76. Mr Allen went on to place reliance upon the CTRL data as illustrating the seasonal pattern of levels going up in winter reflecting rehydration and down in summer when desiccation takes place.
77. In fact the pattern of movement between October 2003 and January 2004 is downwards not upwards as would be expected. Mr Allen relied upon monitoring point 18009 as showing an upwards movement between October 2003 and December 2003 as evidence of rehydration but it is clear that if the movement was tree root induced the point would not have moved downwards from December 2003 to January 2004.
78. For the first time in his evidence in chief Mr Allen propounded the theory that contrary to his earlier evidence that the CTRL data provided evidence of a property going down what in fact it showed was that the datum points on the pavement in front of the building was going up rather than the property going down!
79. Mr Allen's reliance upon the CTRL data was selective. His condemnation of the methodology adopted by CTRL was not justified.
80. I prefer the evidence of Mr Ainsworth. There is no reason not to take the CTRL readings at their face value as monitoring results provided by professionals in a high profile project. They show the degree and direction of the movement following the second tunnelling operation.
81. There was no monitoring evidence as to vibration, or as to movement in relation to the first tunnel.
82. If Mr Allen is right there was sudden and significant damage to the rear and right of the house caused by tunnelling and/or broken drains, whilst contemporaneously and separately there was significant tree root induced subsidence to the front and left side of the house.
83. Whilst all parties accept that 2003 was an event year with more subsidence claims in that year than in an average year it is a far cry to conclude on that basis that the cause of the damage to the Claimant's house was tree induced subsidence.
84. The crack monitoring relied upon by the Claimant showed that there was some evidence of closure in February 2004 which is consistent with heave. The crack closure related to part of the porch and the degree of closure was small, less than 1mm.
85. Two out of five cracks (one and four) showed signs of closure in the vicinity of monitoring point 18008 on the CTRL monitoring. Before the cracks closed by less than 1mm in February 2004 that point had dropped by 14mm between October and 14 January 2004 and by 2mm between December 2003 and 14 January 2004.
86. Mr Ainsworth's view was that the crack readings whilst consistent with evidence of some degree of hydration sufficient to close a gap they do not in fact indicate that it was of such a degree as would have caused the crack in the first place. Mr Kelly, the Claimant's expert arboriculturist agreed that the crack closure of 2004 was inconclusive given the low amplitude of crack closure recorded in the readings, and Mr Hope, the Defendants' arboriculturist accepted that there was an area where there was slight seasonal movement indicative of some desiccation:-

"... I have to accept there is a possibility at that point that there was some significant desiccation ... because a small area moved."

87. He implicated the Claimant's Tree of Heaven five metres from the porch as being the probable cause of this.
88. The Defendants expert at the trial but not in his report implicated vibration caused by CTRL tunnelling of the second, down tunnel as being responsible for the physical damage caused to the fabric of the building. The implication in the report was that the removal of support by tunnelling caused the subsidence that led to physical damage. Mr Allen for the Claimant produced a paper relating to road vibration on which he based his responsive opinion that the vibration could not have caused the damage to the house fabric because the auditory evidence would tend to indicate that the vibration resonance was not sufficient to indicate vibration of such vigour as to cause direct physical damage to the fabric of the house. CTRL evidently did not consider vibration per se as giving rise to a risk of direct physical damage to the fabric of No. 18 and no vibration monitoring was undertaken by them. Had the vibration element of tunnelling been considered an effective contributory cause then this would have been addressed directly by the Defendants' expert in his original report and doubtless if the risk was real would have been the subject of monitoring by CTRL.
89. What is clearly important is to consider what the state of the soil sub structure was in September/October 2003.
90. After an event summer there would have been some desiccation both in the underlying London clay and in the made up soil in which the foundations, such as they were, sat. Contributing to that state of affairs at the front and left would be both the Claimant's Trees of Heaven and the Defendants' London plane trees.
91. The load bearing capacity of the ground would be significantly compromised by reason of the soil desiccation.
92. The engineering experts agree that the effect of CTRL tunnelling operations allied to the root effects of the rear vegetation and the state of the drains causing leaking, were likely to have caused the damage to the rear of the house. The Defendants' trees were not implicated in such desiccation and subsidence as led to the consequential damage to the fabric of the house. As to the front and left the debate was muddied because of the experts' focus on identifying the predominant cause of damage to the Claimant's house.
93. I accept that in 2004 that the Defendants' trees became the predominant and effective cause of desiccation and rehydration as evidenced in the level readings from the winter of 2004/2005 onwards.
94. In my Judgement the removal of the Tree of Heaven in August 2005 by removal of competition may have enhanced the effectiveness of the existing contribution of the London plane tree roots of both Defendants' trees in a complex balance of factors.
95. I am driven to the conclusion that the Defendants' London plane tree roots effectively contributed to such desiccation at the front of the house and left hand side allied to the effect of drain water leakage that enabled the trigger of the tunnelling operations to have a sudden effect upon the vulnerable foundations and damaged load bearing of the underlying sub soils.
96. Whilst the contribution to the damage to the soil structure from each of the Defendants' trees was both effective and material. In 2003 it is likely that it was not the predominant cause.
97. The removal of the Tree of Heaven in August 2005 which had masked the contribution of the Defendants' tree damage became so obvious that all experts agree that thereafter, there could be no question as to the effective and predominant cause of desiccation and heave. The tree roots that were found in the trial pits dug adjacent to the front and left hand side of the building clearly showed London plane tree roots. DNA testing undertaken to identify whether the tree roots being related from the First or the Second Defendants trees was inconclusive.
98. The arboriculturists agree that in the absence of such identification evidence the roots could have been from either or both and in the degree that each contributed to the damage must be considered equal.
99. The Claimant's case is since the affected property was on London clay and the London plane trees were large, and not situated far away from the Claimant's property which was likely to have shallow foundations this gives rise to a foreseeable risk of damage.
100. Clearly it gives rise to the possibility of damage. Both Mr Kelly, the Claimant's arboriculturist and Dr Hope, the Defendants, agreed that prior to damage occurring both the First and Second Defendants would or ought to have known of the potential for trees to cause damage to nearby buildings on clay soils and that there was no reliable methodology for predicting precisely which trees would cause damage to buildings.
101. An attempt by the Arboriculturist Association to develop a computerised model capable of assessing the future risk of subsequent damage to buildings was abandoned because it was demonstrated as being impossible to predict. The study involved eminent mathematicians, computer experts and arboriculturists.
102. Mr Kelly's view was that pruning and crown reduction is and was not the solution, it serves to stimulate growth in fact.
103. Removal of the trees it seems is the only reliable way of removing the risk of damage.

The Second Defendant, Local Authority

104. In an area like Highbury New Park with established gardens with mature vegetation and Victorian houses, roads lined with London plane trees a responsible local authority mindful of its obligation under Town and Country Planning Acts and the preservation of such amenities as an established treed environment could not reasonably contemplate the desertification of such a neighbourhood by wholesale tree felling to avoid a possible risk of damage. Such an approach it seems commended by the Claimant almost gives rise to strict liability.
105. Pre 2003 a reasonable local authority in administering a conservation area such as that containing Highbury New Park would have been fixed with the knowledge of a possible risk of damage from its street trees. As to No. 18 it was not until the 3 June 2005 that the status of protected trees namely the Second Defendant's London plane T1, and the Claimant's own Tree of Heaven T6 became the subject of inquiry. The Claimant gave notice that the Tree of Heaven was to be removed and permission for felling was given.
106. The Second Defendant's own street trees were not implicated at that stage. There is no evidence to suggest that they were uncooperative or were possessed of information that made a possible risk of damage a real risk.
107. Whilst 2003 may have been an insurance event year that would be no warrant for destroying the London planes in the neighbourhood of No. 18.
108. In June 2006 a felling request was made by the Claimant in relation to the false acacia in the rear garden of No. 18. The application was made by the Claimant's arboriculture advisers but resisted by the Claimant herself. She too was entitled to value the amenity value of her trees.
109. I am satisfied that from the evidence of Dr Hope from the proximity of the false acacia tree roots at the rear of No. 18 adjacent to the foundations that it played a material part in causing the damage to the rear of the building.
110. In 2007 a conservation area application to fell was made in respect of the First Defendant's London plane T4 (T1). The Second Defendant imposed a Tree Preservation Order on 3 July 2007. The Claimant's arboriculture advisers objected to the TPO on technical grounds. They did not identify the damage to No. 18. The Claimant's loss adjusters internal report at that time states:

"The technical evidence supplied to date is not considered robust enough to implicate the London Plane Tree T4 (T1) to be removed as has been suggested."

111. The order was not appealed.
112. It was not until 2 April 2009 that the Second Defendant was written to suggesting that its street trees may be implicated together with that of the First Defendant's in causing damage to No. 18. A reasonable request was made for the provision of information implicating the trees. This was not provided until 2 March 2010.
113. The delay may well have been caused by the expressed doubts entertained by the Claimant's insurers as to the strength of their case or it may have been the result of the dilatory way in which Mrs Berent's claim was investigated and pursued between 2003 and 2011.
114. The major consequential damage to the structure of the house was complete by the Spring of 2004.
115. There is no basis, in my judgment, to infer that the Second Defendant's knew or should have known that there was a real risk that its street trees and their root system had caused or would cause damage to the Claimant's property and building either alone, or in conjunction with other tree systems.
116. After the letter of 2 March 2010 as a reasonable local authority they would have been aware that there was a real risk that their trees and that of the First Defendant would continue to cause damage to the Claimant's property namely by varying its load bearing capacity by desiccation and heave and further consequential damage to the structure and fabric of the building.

The First Defendant, The Housing Association

117. They came into the picture earlier than the local authority. As a housing association with an estate comprising period properties such as No. 20 Highbury New Park and others, and more modern dwellings they would as prudent public landlords have been in a similar position to the local authority so far as knowledge is concerned and access to expert arboriculture advice.
118. Pre 2003/04 there is no evidence that would warrant the inference that their awareness of a possible risk of damage to the neighbouring property at No. 18 was translated into an actual or imputed knowledge of the real risk.
119. The earliest date that the First Defendant's knew that its London Plane Tree T4 (T1) was implicated in the damage to the fabric and structure of No. 18 was the 17 January 2005 when the Claimant's wrote notifying them of a possible link.
120. The Claimant's Tree of Heaven was removed in August 2005. The Claimant's loss adjusters in December 2006 were doubtful as to the actual cause of damage. In an internal memorandum it is recorded that:

"Engineer has advised that the worst damage is not tree related and front entrance is underpinned. We need more up to date mons to demonstrate role of T4 particularly post removal of Tree of Heaven T6 and drain repairs."

121. In January 2007 level monitoring evidence and analysis demonstrated feasible desiccation and heave resulting from tree root. The engineer clearly changed his mind. The expert engineer and arboricultural evidence in this case confirms that he was right to do so. However a prudent public landlord on the basis of a possible link and the state of knowledge entertained by the Claimant's own experts cannot be criticised for awaiting information enabling them to take focused remedial steps if shown to be necessary. Mr Kelly, the Claimant's arboriculturist accepted in cross-examination that the First Defendant could not be expected to remove a tree until a reasonable level of information had been provided.
122. It took two years before the First Defendant's reasonable questions were answered on 23 January 2007.
123. By June 2007 the Claimant's had decided in any event that they were going to underpin the damaged property. That course however, was not pursued. A two year lack of contact between the parties led to the First Defendant's loss adjusters in February 2009 concluding that the matter was no longer being pursued and they sent in their final account.
124. In July 2009 the First Defendant applied for the removal of T4 (T1). The Second Defendant indicated that further information would be required to justify felling and later indicated that consent to lopping would be given which allied to monitoring might give further information as to the implication of T4.
125. The nearest building to T4, of course, is the First Defendant's building of similar age and size to No. 18. It is noted in the correspondence that there is no damage to that building such as might put the owner of that building and tree on enquiry as to neighbouring properties.

Conclusions – Liability, Second Defendant

126. The local authority I am satisfied had followed a prudent regime of tree management by pruning. By April 2009 after notification it was clear that its trees were implicated and that felling was the only way in which the nuisance could be abated.
127. In fact it was not until 9 February 2011 that the Defendants gave notice of intention to remove their trees. It would have been reasonable to remove them in the late Autumn of 2010 and the failure to do so gives rise to breach.

First Defendant

128. The Claimant's arboriculturist on 26 June 2007 wrote to the Second Defendant's loss adjuster saying:

"Our client is now advised that they are proceeding to underpin the damaged property. We believe that we have given your client a sufficient amount of time to abate the reported damage. Our file is now closed. Please contact our client directly in the future."

129. On 14 September 2007 the Claimant was asked to provide further information on the remedial works proposed and the monitoring. In particular they asked about the crack and level readings and the drainage pattern and the results of the DNA testing on tree routes.
130. On 27 July 2008 no reply having been received the Defendant's insurer telephoned the Claimant's representatives asking whether they were still pursuing the matter.
131. Two days later on 24 July 2008 the Claimant's loss adjusters emailed the Defendant's insurers in the following terms:

"Hi Rob

I had a message to update you regarding the third party trees. We were unsuccessful in getting agreement to tree removal. We did refer the claim to our recovery unit but on review the prospect of a recovery is too low to pursue as we do not have enough evidence to support our case so the recovery file has been closed.

We have had the site visit with our surveyor Mike Hayes and the contractors. The policy holder has provided their excess and mandate and upon receipt of the schedule from the contractor we will be able to proceed with the repairs. If you have any further queries please don't hesitate to contact me.

Regards ..."

132. On 5 February 2009 there being no response for two years the First Defendant's loss adjusters assumed that the file was closed.
133. Since underpinning had been chosen obviating the necessity for tree removal no criticism can attach to the First Defendant in relation to T4. In view of the representations made by the Claimant's advisers and their failure to provide information reasonably required for the First Defendant to consider the appropriate means of abating any nuisance caused by their tree the response of the First Defendant cannot be characterised as unreasonable. Indeed, they did all that they sensibly could given the state of investigation to abate the nuisance. In taking account the First Defendant's position in relation to abatement I have of course taken into account their endeavours to remove the tree which was the subject of a TPO and located within a conservation area.
134. By the beginning of 2010 it should have been known that piling in fact was not put in train so that the reasonable obligation would involve the felling of T4.
135. I see no reason to distinguish between the position of the First and Second Defendants so far as abatement and tree felling is concerned. Thus by failing to abate by the Autumn of 2010 I find them to be in breach.

Quantum

136. The evidence of Mr Allen and Mrs Berent is that the principal damage was done in 2003/2004.
137. Thereafter the pattern of desiccation and heave summer to winter served to open and close the cracking.
138. There is no cogent evidence before me to show that the degree of physical damage to the structure and fabric was increased during the many years of abortive investigations, intermittent monitoring and gross inconvenience suffered by Mrs Berent from year to year. There would be a minimal amount as cracks would have been filled and minor remedial works undertaken and the dwellings made more habitable from a cosmetic stand point.
139. Such consequential damage was not caused by the breach.
140. The gravamen of this case is that Mrs Berent was forced to endure damage to her home and her investment properties and great anxiety between 2003 and 2011.
141. She is entitled to damages for gross inconvenience and loss of amenity as a result. That attributable to the Defendants' breaches is from the Autumn 2010 to the present. I award £5,000. The responsibility for the loss of amenity and gross inconvenience for the intervening years lies elsewhere.
142. Had I been required to decide which of the remedial schemes was appropriate I preferred the evidence of Mr Ainsworth to that of Mr Allen.
143. Mr Allen's scheme was proposed on the basis that because of the gross delay in investigating this claim his scheme arguably caused less inconvenience to Mrs Berent. Since the delay was not the responsibility of the Defendants the Claimant can only recover the cost of that based upon the removal of the trees, the cosmetic internal repairs and the final repairs after the cycle of desiccation and rehydration has taken place.