leylandii laws & boundary walls

[robertson]

What are the current laws governing the height of leylandii trees, how are those laws imposed, and how can you tell which boundary wall belongs to which (detached) property?

[buildersmate]

Leylandii hedges
This is far more complex than a simple statement about the height. Read here and post again if you have further questions for the forum. See particularly the FAQ section.
http://www.communities.gov.uk/index.asp?id=112 7822

Boundary walls
The first place to look is on the Plan that the Land Registry holds of your property (assuming your land is registered). It may tell by means of an annotation against the boundaries that you are responsible for. That is not the definitive answer though because it is perfectly possible that an owner whose boundary is not built a wall INSIDE the boundary line.
The best advice is to discuss it with the neighbour in question and understand his/her perception than use that to discuss. You can't easily use the Land Registry to determine the 'truth' if the boundary line is unclear (because the maps aren't that accurate), and engaging legal bods to sort it out is hideously costly. Post again the describe the detailed problem, if necessary