The Brits are at it again!
http://www.iht.com/articles/102653.htm
Hedge-rage hits Britain! One suit causes Court to define "hedge!"
What ever will they get up to next!
Here in *New* England anything over six feet is called a "spite fence" and if you build one they will come and make you top it off to the allowed height.
If your trees or hedges are the problem most N.E. towns have the right to trim to specifications or trim to remove branches obstructing a sight line as at a corner where there is merging traffic or where an official road sign (stop/ speed limit/etc) is being blocked.