A plane in Mayfair has been valued at £750,000, making it Britain’s most valuable tree.

The valuation of the 6ft-wide tree, which has graced Berkeley Square since Victorian times, is based on a new system devised by local authority tree officers. It takes into account size, health, historical significance and the number of people living near by to enjoy it.

This valuation system, known as the capital asset value for amenity trees (Cavat), is to be adopted by every local authority in the country to prevent the massacre of trees blamed for subsidence in buildings.

In future, the high value of trees will demand extra engineering work by insurers to prove a link between a tree and subsidence. Other common causes for subsidence are broken drains and dry weather.

Healthy mature trees are being felled by risk-averse insurers and councils because of suspicion that they are causing damage to neighbouring properties. In future a well-loved street tree will only be felled if an insurance company can prove that it is the real cause of the subsidence.

Andy Tipping, chairman of the London Tree Officers’ Association , said that too often insurance companies facing a claim for subsidence were demanding that trees be destroyed. Councils were also too willing to cave in to insurers’ demands.

In London alone the value of trees is estimated at £6.4 billion under the new system. Besides planes the most valuable trees are oaks, horse chestnuts and beeches.

There are many valuable oaks scattered throughout Central London. An oak in Southgate, North London, has been valued at £267,000 and a plane in Epping High Street £200,000. Most street trees are worth between £8,000 and £12,000.

In the past five years London councils have chopped down almost 40,000 street trees, including some more than 100 years old. Some were just old or dying but 40 per cent were removed because of insurance claims. A report commissioned by the London Assembly challenged this figure and said that only 1 per cent of tree removals were justified.

Mr Tipping believes that the new formula will help householders and insurance companies and save trees for neighbourhoods. “Often an insurer will point the finger at the tree, it is chopped down and then subsidence problems in a house persist,” he said. “Companies pay out vast sums repairing buildings and then some months later new cracks appear. Under the new scheme there will be more on-site investigations to find the source of damage at the beginning of a claim.”

Mr Tipping, a tree officer in Barnet, said that the new system might also stop the disputes between insurance companies and tree officers about the cost of site investigations. In one case he was asked to remove a 130-year-old oak that was three houses away from a property with subsidence, yet there were no roots near to it.

“It’s an absurd situation,” he said. “People are still not understanding that subsidence is a problem of buildings not trees. In many cases trees are not the main culprit. It’s other reasons such as Victorian drains, poorly installed double glazing or climate change.”

Putting down roots

Top 10 trees bought today for streets and parks

1 Plane
2 Hornbeam
3 Oak
4 Beech
5 Yew
6 Western red cedar
7 Horse chestnut
8 Field maple
9 Ornamental pear
10 Flowering cherry

Top 10 trees found in streets and parks

1 Leyland cypress
2 Hawthorn
3 Sycamore
4 Silver birch
5 Common ash
6 Lawson cypress
7 English oak
8 Japanese cherry
9 Beech
10 Holly

Source: Civic Trees/Department for Communities and Local Government

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