"bigjon" wrote in message
...
... My questions - was he legally allowed to basically destroy a
healthy tree in this way, as it did not cause any real problem to him,

Yes. He is permitted to cut back anything that overhangs his side of the
boundary. It is technically theft if he does not then return the cuttings to
you, but I would not expect the Police to be interested in pursuing it as a
crime.

and
should I remove the top branch to allow another to become the lead ?

If the tree is that badly affected, I would bring in a tree surgeon. It
probably needs an expert to see it to get the best advice.

Colin Bignell