I don't think there is a legal max. height for trees, Guest, but planning regulations say that you can only put up a 2m fence, and I believe it may be the same for hedges. I'm not 100% sure, though. You could check with your Local Authority for your area.

This seems extremely helpful

http://www.herefordshire.gov.uk/environment/23592.asp

check with your local council if you let your hedges grow to high you could end up in trouble.especially if the neighbours complain

So I was right about the 2 metres. I thought that was the case.

I think it is reasonable to say it is 2 metres or lower if the deeds on your propert say so. The problem is most councils want £300 to take action against people in breach.

This is ofcourse a farce but par for the course with bureaucracies.

Its 2 meters in the back and sides around here but the front is different again as it can be none at all or as little as 2ft if its a relatively new build?

Yes in many estates ,some as old as 20 years there are total restrictions on planting of hedges in front gardens.