For a more complete clarification on UK law;
In England and Wales, there are two systems of law. COMMON LAW and STATUTE
LAW. Both affect trees in some way, but it's the common law which covers these bits...
COMMON LAW
Common law is based on case law and the decisions made on those cases by judges over the years.
Aspects of Common law which are of relevance to trees include;
Ownership, Overhanging Branches (and Roots), Damage caused by Trees.
Ownership of Trees
A tree normally belongs to the land on which it is growing.
The position of the trunk, where it emerges from the ground determines ownership.
Where a tree is growing on a boundary and it is not possible to say on which side it arose, the ownership of the tree may be shared between the two parties.
The owner of the tree is entitled to the rewards from the tree; eg: Timber and fruit.
Overhanging Trees.
If trees in your neighbours garden overhang your property, you are entitled to cut off the overhanging branches. Any fruit or timber from the branches belong to your neighbour.
Rhys
"When one burns one's bridges, what a very nice fire it makes" -- Dylan Thomas
"As to marriage or celibacy, let a man take the course he will. He will be sure to repent" -- Socrates