nthng2snet wrote:
I would like to build an extension to the rear of my house. I don't
think the next door neighbour would agree to me building on the
boundry line, in fact I want to avoid the issue with him altogether.
How far from the boundry line can I build without having to seek his
permission. I have read that this is 300mm but can't find any
information from the odpm.gov. website to confirm this.

Do take account of any overhang of the roof of your new extension.
A friend of mine didn't. At the last minute it was pointed out that the
new roof would overhang the (reasonable) neighbour's by at least 15"
(inc gutter).
The plans had to be hastily modified to move the new wall back and
changes/delay worked out quite expensive.