Alexandra Gardens is a late Victorian/early Edwardian park laid over an old brick pit. The surrounding land, rising slowly from the River Cam, is mostly riverine clay with some patches of sand. Our research showed that many Victorian houses in the locality (which is one of the very few mild inclines in Cambridge) show cracks due to the seasonal hydration and dehydration of the clay soil, whether they are near trees or not.
Mostly these are repaired and painted over but sometimes, in more serious cases, underpinning is required. However, aggressive insurance companies seek to avoid paying for their clients' repairs by claiming that neighbouring trees are causing the damage. They demand that the owner either pays for extensive underpinning work, or fell or seriously cut the trees, removing most of the branches.
Case law currently favours the house owner - or more correctly, the insurance companies. If roots "trespass" near a property, then the law considers that the trees, in the balance of probabilities, are contributing to the "nuisance" and therefore must be removed. A Supreme Court judgment in 2014 (Coventry v Lawrence  UKSC13) offered the possibility that the law might be shifted. In the case of the trees at the back of the Gardens - backing Alpha Road - in 2015, we sought to pursue this through the courts and persuade the council to fight these opportunistic claims by insurance companies. We were generously and vigorously supported in our campaign by local environmental law practice Richard Buxton Solicitors. In the High Court, we lost our case. Here is the summary of the judgement by Mr Justice Ouseley. As it stands, the law is slanted in favour of the insurance companies which have relentlessly used legal campaigns to establish precedent.
The soil science is rather complicated but the law is in this case a particularly obstinate ass. The result is that majestic mature trees are being unnecessarily cut down or their crowns reduced drastically without real reason. Very often, the cracks caused by clay soil movement under hydration-dehydration cycles are only superficial and merely need re-pointing or filling. An extensive report written in 2011 - amid a previous threat to the tree on Carlyle Road - by one of our AGTG members, Dr. Adrian 'Sam' Hill of Cambridge University, going into considerable detail of soil hydrodynamics, supported our case to the extent that the Council (then under a previous administration) listened and agreed to settle the claim with the insurers.
As the law stands, a house owner (and this has happened with affected properties around Alexandra Gardens) can build a modern extension to a late Victorian house over ground already occupied by tree rootlets (which absorb moisture from the ground) from a fully mature tree nearby. The resulting mismatch between modern and Victorian foundations may then cause plaster cracks. The insurance company - wanting to avoid paying for remedial work to the property - claims that the rootlets are causing soil movement and sues the tree owner (in this case the Council). The law at present says that if a tree rootlet is present on the house owner's property, then it is responsible for the damage. The fact that the house was altered significantly after the house and tree had existed side-by-side without problem until then is not admissible as a defence. We sought to persuade the Court to extend the law of "coming to a nuisance" which allows that if a person moves to a place where a pre-existing "nuisance" is present (for example, a noisy race track that has been there for a long time), the person cannot reasonably ask the nuisance to be abated. This does not extend to trees and roots at present. We failed in our attempt to change this.
Don't let insurance companies deny us their beauty. Please help us to oppose and reverse proposals to damage the trees. If you support our cause, or want to find out more, please contact us.
Other links and background information:
A short history of Alexandra Gardens (Parks and Gardens)
SOS Cambridge (local group supporting green spaces)
London Tree Officers' report; "A Risk Limitation Strategy for Tree Root Claims"
Tom Armour (leader of global landscape architecture for Arup) "Cities Need Large Trees"