The LTOA, which aspires to establish a high profile for London’s trees and woodlands, argues that the more valuable a tree, the more effort engineers must put into seeking the real source of subsidence before reaching for the chainsaw. But how does one value a tree? First, you measure the size of the trunk. Multiply this number by the height and work out the worth of the wood you are looking at, at £12,55 (€15,80) per cubic centimetre. Another factor is how many people look at the tree every day. Then use your skill and judgement as a tree officer to adjust the value up or down taking into account the tree’s health, location and status as a member of the community.

The system has valued a plane tree in Berkeley Square, Mayfair, at £750,000 (€944.264), reflecting its giant size, condition and the number of people who see it every day. The combined value of trees in London - where the scheme is being trialed by four boroughs - is reckoned to be £6.4bn (€8.05bn).