I can't judge the position visually - the overhang, if it does actually exist,must I think be extremely small - but I'm uncertain as to the best way to proceed. The neighbour has asked that I raise the matter with both the builder and the architect and I'm quite willing to do so, but it seems to me that the architect isn't really involved and the builder is hardly the most unbiased person to pass judgement on the situation.
Isn't it up to my neighbour to prove his contention? If so, I assume this would take more than just his word on the matter and a visual inspection. I doubt the builder would accept anything less than an independent surveyor's report, and in fact neither would I.
But I'd be grateful for any comments. Many thanks.