Whattodowithaminute, I know what you mean, I does make you feel like moving. If/When I when the big one on the premium bonds that is exactly what I will do. In the meantime I have to try and feel sorry for him, as many of you point out, he clearly has too much time on his hands - actually he was a lawyer now working locally on a wind down to retirement type job and he clearly misses telling people what to do and using legal language to do so. Next spring, budget permitting we will be erecting a large pergola, for which we don't require planning permission or his permission, we aren't doing it to annoy him but because we are in the lucky position of having a sunny garden and it will provide some shade for dining BUT the rules allow us to build it 2.5 metres high and right next to his fence.. whereas our build is 2.4 metres 800mm from his fence, lovely recycled and cleaned London Stock, but he doesn't have any vision. Later, budget permitting again, we will replace the shed we had to loose with a almost full garden width studio/shed which can also be built 2.5 metres near to the boundary and does not require planning permission. Again not to annoy him but because with three children late teens to early twenties having this as their base between Uni and first jobs, it will be a lovely space for all to escape/gym/yoga or just quietly read a book. His reaction to both the pergola and the studio will be interesting. Van, I keep walking round our extension and wondering whether we should have removed bits and changed bits, and there is a steel that will show on one wall we weren't expecting, it is hard to really visualise how it will all look with furniture in - I can't decide which side to put the dining table for example, and that impacts on whether and where a tv goes (I don't really want one, but am outnumbered). Builders working today, the first and only Saturday they are likely to, water was off for an hour and I had to show a plumber round the house in my dressing gown 
. Good luck with the boundary issues and the neighbours.
Ironically neither of our neighbours served Party Wall on us and both should have done.... the neighbour on other (since moved) someone runs his own very successful building company that specialises in extensions, but he built 50 cm longer and 50 cm higher than permission, he had to knock down the roof and lower it! He moved to a large expensive detached on the back of the money he makes doing other people's extensions (not physically, he employs gangs of labourers to do the work), his linkedin profile says he is a director and a surveyor - he has no surveying qualifications, he lies, he cheats and he ignores planning. Very glad that he moved, new owners on that side are such an improvement. Makes so much difference.