A Response to the London Assembly Environment Committee Report
“Chainsaw massacre – A Review of London’s street trees - May 2007”
By Mark Briggs, National Operations Manager, OCA UK Limited
My name is Mark Briggs and I am the National Operations Manager for OCA UK Limited. I have
worked within the Arboricultural industry for sixteen years, with five of those years being spent
working as a Tree Officer with the London Borough of Redbridge and eight working with OCA.
OCA UK Limited has been trading for fifteen years and is the leading Arboricultural Consultants
Practice in the UK. OCA UK Limited is involved in the investigation and mitigation aspect of
around 4,500 claims for tree related subsidence damage annually. Our clients include the major
UK building insurers, loss adjusters and Consulting Building Engineers. 60% of all our
instructions relate to subsidence events in the South East of England with at least half of these
occurring within the Greater London area. Although only 30% of our instructions relate to trees
owned by Local Authorities this still equates to just over 400 claims per year in which trees
owned and maintained by London Boroughs are implicated as the cause of damage. Therefore
OCA UK Limited and I as the National Operations Manager have a vested interest and are
qualified to make comments relating to all issues concerning tree related subsidence. It is for
this reason that I have reviewed and responded to the London Assembly Environment
Committees Report, Chainsaw massacre – A Review of London’s street trees.
Is London losing its street trees? The report answers its own question with two very definite
statements “The short answer is no. Overall London is not losing its street trees”. This is then
followed by a further statement “…there has in actual fact been a net gain of 8,000 trees planted
across the Capital in the past five years…” Therefore I find the title of the report both misleading
and disappointing and I wonder whether it was devised as a headline rather than a working title.
Recent press coverage seems to suggest the former. However, despite the opening statement
the report goes on to explain that the ‘net gain’ is not evenly spread and that some London
Boroughs are felling more trees than they are planting. The report then discusses and gives
recommendations relating to these two issues, felling and planting.
In the Chair’s foreword reference is made to broadleaf trees only and no explanation is given as
to why London’s coniferous trees were being excluded. Both broadleaf and coniferous trees
absorb carbon and therefore have an equal role to play in pollution amelioration. In fact there is
little evidence to suggest that broadleaf trees provide a greater benefit to the environment and
public health than do coniferous trees. The foreword also makes reference to Plane being a
native species, it isn’t and I presume that this was an oversight on behalf of the author.
Valuable data is provided in Table 1 and Table 2 and I fully endorse the recommendation that
the London Tree Officers Association make this information publicly available on an annual
basis. I am a true believer in the sharing of any data relating to street trees, especially in relation
to subsidence and would welcome the opportunity to present and share the OCA UK Limited
data with both the London Assembly and the London Tree Officers Association.
I was confused as to why ‘Current protection for street trees’ was included in the report as, as
stated at 2.9, very few street trees are the subjects of Tree Preservation Orders. However, in
those instances where a Council wishes to undertake works to a protected tree under its
ownership but also acts as the Local Planning Authority, they are no longer required to make an
application to the Secretary of State under Article 6 of the Model Form of the Tree
Preservation Order 2006 (as was the case under the 1969 Regulations). Instead the Council are
required to post site notices stating why works are proposed and take into account any
representations made during the minimum 21 days of consultation period. However, it would
still be the case that unless the Local Authority gave its express permission, no works to the
trees would be allowed to be undertaken by a third party. In relation to Conservation Area
controls, the Town & Country Planning (Trees) Regulations (1999) Regulation 10 (d) exempts
the cutting down of trees for by on behalf of a Local Planning Authority therefore no
notifications are required. I suggest that it may have been more appropriate to refer to the
various statutory instruments that applied to street trees. For example section 96 of the
Highways Act 1980 states that a Local Highway Authority has a duty to plant and maintain trees
in the public highway, the legal reason that Council’s can and do plant street trees. Section 96 of
the Highways Act 1980 also states that the Local Highway Authority has an obligation not to
allow its trees to cause an actionable nuisance to third parties. Both these examples are more
relevant when considering the content of the report.
Although the report purports to be both independent and objective (Annex D) there is a clear
bias towards subsidence and the insurance industry being a major reason for the removal of
London’s street trees. This overriding theme begins in the Chair’s foreword and continues
through the first half of the report (sections 1, 2 & 3) despite no corroborative evidence being
provided to support it. Indeed when reviewing the data presented in Table 2 it can be clearly
seen that of the 39,924 trees removed in the capital over the past five years 75% were felled
because of health and safety and only 5% were removed because of subsidence claims. I note
with interest that no reasons have been given for why the remaining 20% of trees were
removed, in fact these trees are not mentioned anywhere in the report. If, as stated at Annex B,
one of the intentions of the review was to identify whether there had been any loss of street
trees in London and if so, what the reasons for this loss were, surely health and safety
warranted more than one brief paragraph and ‘other reasons’ should have at least got a
mention. The statement that “Boroughs will undertake surveys of trees to see if they pose a health
and safety risk before determining if they should be removed” is vague and I would have expected an
explanation of what methods were in place to assess and manage health and safety risk. Given
the reports later recommendation that “Boroughs should do everything within their power to prevent
the loss of street trees…” I think that the questions need to be asked; was the risk presented by
these trees unacceptable? And was it really necessary to fell them all? From my own experience
it is the case that many trees are removed on health and safety grounds when they could have
been safely retained, managed and monitored.
Despite the data showing that only 5% of the total numbers of trees removed over the past five
years were removed due to subsidence the report devotes twelve paragraphs to this subject.
Within these paragraphs comments are repeatedly made referencing poor levels of evidence
supporting requests to remove street trees that are implicated as a cause of subsidence damage.
This includes the misleading, and factually incorrect comments made by Andy Tipping, the Chair
of the London Tree Officers Association.
My own experience of dealing with tree related subsidence claims in the London area over the
past eight years is that nearly all notifications made to Local Highway Authorities by OCA UK
Limited are supported by evidence that satisfies the necessary ‘legal tests in causation’ that the
civil courts have established.
Of course I can only speak for those incidences in which OCA UK Limited has been involved
and it is possible that notifications made by others may not be supported by the same level of
evidence. However, if levels of supporting evidence are so low, as the report suggests why is it
that 2023 trees were removed over the past five years due to subsidence and why are insurers
able to successfully recover significant costs from the London Boroughs on an annual basis? In
addition the report fails to make any reference to the legal precedents and case law pertaining
to tree root nuisance and in doing so appears to ignore the fact that despite industry or other
guidelines, levels of evidence are set in the courts not by Local Authority Tree Officers. I refer
to the statement made at 3.6 “A number of tests are required to prove conclusively that a tree may be
the cause of movement”. This statement is factually incorrect as tree root nuisance claims are
dealt with under ‘Civil’ law whereby evidence need only demonstrate that, on the balance of
probabilities a tree was an effective and substantive cause of the damage. Conclusive proof infers
the ‘beyond a reasonable doubt test’, which is what ‘Criminal’ law requires.
Clearly subsidence is a reason that trees are removed and the report is correct in its statement
that “…in some locations in London the problem is more acute…”. Indeed our own data suggests
that even within any of the London Boroughs the highest incidence of subsidence claims usually
occurs within two or three postcode sectors. The review is also correct in its statement that
“the perceived threat of subsidence is much greater than the actual threat…” and the data provided
in Table 2 suggests that the number of trees removed due to subsidence equates to 0.5% of
London’s total street tree population (possibly 0.1% per annum). It would be interesting to
discover what percentage of the 2023 were felled as a result of claims arising during the
2003/2004 event year and whether the number of trees felled due to subsidence in subsequent
years was lower.
I have yet to fully the review the London Tree Officers Association risk limitation strategy
document but have previously reviewed the CAVAT system following which my comments
were passed to the working group of the LTOA. A copy of my comments is attached at
Appendix 1. In relation to the Joint Mitigation Protocol I welcome the opportunity for OCA UK
Limited to take part in any trial of this system and to provide feedback to assist in its
development. I fully support any joint venture between the public and private sectors which
seeks to reduce the time taken to resolve claims and subsequently benefits policyholders.
In contrast to the above, sections 4 & 5 of the report, which relate to tree planting and tree
management, include some valuable comments and recommendations which I fully support.
These include: Increasing community involvement in tree planting schemes and obtaining funding
for such initiatives; Proper management and maintenance of street trees and increased budgets
to achieve this; Ensuring that new developments include tree planting and maintenance in their
design and planning and the development and adoption of specific tree planting strategies in
London. However, again no reasons are given as to why these strategies should include
broadleaf trees only. It has long been my opinion and the opinion of OCA UK Limited that the
key to the successful, sustainable management of any tree resource, whether publicly or
privately owned relies on a clearly defined strategy supported by robust policies, developed in
association with all stakeholders and administered by suitably qualified professionals. It is
probable that if each of the London Boroughs was able to develop such a tree strategy many of
the issues raised in the report would be addressed.
The London Assembly Environment Committees report ‘Chainsaw massacre’ raises a number of
questions: Why are so many trees removed due to health and safety? What other reasons are
trees removed for? Why is subsidence being highlighted as a major threat to London’s street
trees when it’s not? And why are some Boroughs unable to plant as many trees as others. I feel
that, until these questions are answered it would be unwise to implement some of the
recommendations made by the report, specifically those relating to subsidence. I consider that
the report is a starting point for further investigations and discussions with all of those
individuals and organisations with an interest in the capitals trees. I welcome the opportunity for
OCA UK Limited to become involved in these investigations and discussions.