As a trainee volunteer hedgerow surveyor, I was taught that it’s a tree if it’s over 5 metres and if it’s under, it’s a shrub. That’s one definition.
In 2009, Mr Justice Cranston gave a ruling in the High Court on what a tree is, a totally different definition:
However, HS2 Ltd and their contractors apparently have a third view, as an arboriculturist explains in the video, and in practical terms they can cut down what everyone else would call a tree!