There is no such thing as an entirely safe tree. Branches (and indeed, trees) will fall and sadly, it is a fact of life that this can lead to serious injury and on occasion, death. Yet the risk posed by trees is extremely low. There is a one in 10 million chance of an individual being killed by a falling tree (or part of a tree) and just over a one in a million chance that this will lead to an accident and emergency admission – approximately 55 per year. 
There can be no doubt however as to the value of trees, both from a health and wellbeing perspective and given their benefit to the environment. Care should be taken not to over-state the risk that trees pose as this has the potential to result in the “defensive” management of their tree stock by landowners, to the detriment of us all.
A landowner’s duty of care
It is against this background that landowners are under a duty to “take such care as in all the circumstances of the case is reasonable” to see that visitors to their land are “reasonably safe” as set out in the Occupiers’ Liability Act 1957. At the heart of this duty is the need for a system of tree safety management through inspection. Such a system must have regard to the hazard (in this case the tree) and the likelihood of that hazard causing injury or damage, thereby resulting in an assessment of the risk posed by the tree. This calls for a risk-based approach as a hazard in one area, perhaps adjacent to a footpath in a busy, urban park presents an entirely different risk to that situated in an area of low footfall, such as a woodland.
Facts of the case
BLM, instructed by Zurich Insurance on behalf of National Trust, successfully defended a claim brought by a visitor to Lyme Park, a Mansion House with formal gardens surrounded by a 1400 acre medieval deer park in Disley, Cheshire. In August 2016, Joanna Parker was visiting Lyme Park with her husband and children when she was struck by a substantial branch that fell from a Horse Chestnut tree, sustaining catastrophic injuries. The case came before His Honour Judge Bird, sitting as a High Court Judge at Manchester District Registry with judgment handed down on 10 June 2021.
The tree was located close to the meeting of two footpaths in a wooded area. It was a warm, sunny day and the family stopped by a stream for the children to paddle, whilst the adults sat on a blanket beneath the tree. The tree was affected by Horse Chestnut Bleeding Canker (HCBC), a common disease which affects Horse Chestnuts. This disease leads to the death of the phloem and vascular cambium, which in turn, leads to decay and this was the mechanism which resulted in the failure of the branch.
The tree was last inspected by the defendant’s tree inspector in December 2014, 20 months before the accident, at which point no action was recommended. Not surprisingly, the defendant’s tree inspector could not recall the inspection and so expert arboricultural evidence was required to determine what would have been there to be seen in December 2014.
It was common ground between the experts that any external signs of decay on the branch, which was located on its top side, would not have been visible from ground level at any point prior to the branch failure. The issue was whether the signs of HCBC, in combination with other ‘defects’ within the tree, were such that a competent tree inspector on inspecting the tree in December 2014, would have determined remedial action was necessary which in turn, would have led to the branch in question being removed.
System of Tree Safety Management
There was in place a formal system of tree safety management based on the National Tree Safety Management policy operated by the defendant. This set the frequency and nature of the inspections depending on the location of the tree. As such, the property was divided into zones, ranging from high and very high, located around the car park and playground areas, where footfall was highest and which required an inspection every one or two years; to the low and very low zones, which included certain of the woodland paths and which would be inspected on a less frequent basis.
It was agreed by the experts that an inspection of the tree every three years, based on a medium zone inspection, was reasonable; as was the manner of the inspection, namely ‘a walk by inspection of every tree looking for obvious defects’. There was therefore no challenge to the system of inspection or the training received by the inspectors; the allegation was that the inspection in December 2014 was not carried out with the requisite care and attention.
Standard of care
The standard of care expected of a tree inspector is that of the ordinarily skilled tree inspector – the ‘Bolam’ test – in accordance with the well-established principle laid down in Bolam v Friern Hospital Management Committee  1 WLR 582. A tree inspector will not be considered negligent if the inspection is conducted in accordance with the practice accepted as proper by a responsible body of arborist opinion.
The claimant’s case was that the defects within the tree (both HCBC and non-HCBC) were ‘obvious defects’ such that a reasonably competent tree inspector would have identified them and required work to be done; or the inspector would have undertaken further investigation by way of an aerial inspection, which would have led to remedial work.
There was broad agreement between the experts as to what was there to be seen in the tree in December 2014. It was likely that any HCBC symptoms present (which would have manifested as lesions or staining of the bark) would have been subtle. The non-HCBC symptoms, namely the existence of large cavities and long branches (described by the claimant’s expert as poorly attached at points of historic failure), were long-standing.
The disagreement was as to the significance of these features and whether they constituted ‘obvious defects’ which would meet the threshold for action. An obvious defect was one that was obvious (i.e. it could be seen) but more importantly, which posed a serious and present risk, particularly where the damage is immediate  (my emphasis).
The claimant’s expert took the view that a reasonably competent tree inspector could not form an opinion on these features from a ground-based inspection, but was required to carry out an aerial inspection by way of further investigation. He considered these hazards needed to be addressed, regardless of location.
The defendant’s expert considered any signs of HCBC present in December 2014 were not an ‘obvious defect’ and if seen, would have been assessed as a low risk, with regard to the location of the tree. He considered the cavities and long branches were not structurally significant and he would again have recommended no action in December 2014. He was clear that an aerial inspection was not warranted.
Court’s findings: no breach of duty
The Trial Judge preferred the evidence of the defendant’s expert in finding that a reasonably competent tree inspector, conducting an appropriate inspection of the tree in December 2014, would not have identified any obvious defect or been required to carry out further investigation, by way of an aerial inspection.
The Trial Judge found that to come to any other conclusion would impose a standard of care on the defendant’s tree inspector over and above that which is accepted as appropriate by arborists. The standard of care put forward by the claimant’s expert was inappropriately high and out of step with modern tree safety thinking, which preferred a risk based approach, as was operated by the defendant. To do otherwise would be to render the system of tree safety management unworkable, both in terms of being too time consuming and too expensive.
Quite simply, the condition of this tree in December 2014 did not warrant any further investigation or action. As such, the defendant had properly discharged its duty to take reasonable steps to ensure the claimant was safe when visiting the park and so the claim would be dismissed.
Commenting on the outcome, BLM Partner Nicholas Thorne said: “This is an important decision which re-iterates the need for a common-sense approach to the management of risks associated with trees. To do otherwise is to set an inappropriately high standard of care for landowners to follow in contrast to the low risk posed by trees.”
Zurich’s Head of Large Loss Injury Tracey Pike said: “We welcome this decision, which supports a responsible and risk-based approach to tree management, rather than an inappropriately high burden for landowners. For landowners to be dissuaded from allowing the public to access woodland and green spaces due to the high costs to them of doing so would be counter-intuitive.”
A full copy of the judgment can be seen here.
 National Tree Safety Group publication “Common Sense Risk Management of Trees” – p22.
 Common Sense Risk Management of Trees – p44.