poseiden
HGMbuild suggests that because it's a new build then the neighbour has to pay for half. I'm almost certain this is not the case. The block next to me hasn't been sold, if I erect a fence I don't think I can ask the person that buys the block for half the money. Would others agree with this??
Yes you are right. Doesn't matter new build or not, must notify in some way prior to putting fence up if you want them to share costs.