Just to update. They haven't yet progressed with the pd work. The builders must have just been assessing the work when they were here before.
In the light of their statement that they were not going to issue pw notice, we rang up the chartered surveyor who we had hired to look at the misrepresented boundary and the planning app. He sent the applicant a letter saying that a pw notice would be required for excavations within 3m of party wall if below foundations. It was a courteous and matter of fact letter.
She sent it on to their previous party wall surveyor who had drawn the dodgy plans in the first instance for planning app. He must have telephoned our chartered surveyor because he refers to a conservation in the letter he copied to us which was issued to our guy. Again saying the wall is not a party wall and they do not need to issue excavation notice, only line of junction notice (and this would be just to inform us they were proceeding). He said again the wall is wholly owned by them; this is the ruddy boundary dispute still, despite the chartered surveyor and the senior planning inspector who saw it regarding it as a party wall.
They are disputing the boundary but without any real substance on which to base their argument. Their party wall surveyor's letter substance and tone is a world away from what one would expect from a professional surveyor. He is quite personal. Saying things like if we part own the wall, then we won't mind paying for it's maintenance so, also saying it's wholly owned by next door because we don't have a structure attached to it. He also says to our guy (who is chartered surveyor, rics etc.), 'despite where you think the boundary is'. Also, 'it is unreasonable to consider what you describe as 'a party structure' to be taken into account with regards to a party wall notice'.
I don't want to have to go to court. Why are these bloody people creating a boundary dispute without proving it or resolving it properly. With a proper chartered surveyor's report at least. It's an issue if we want to sell.
And before anyone says we should just talk to them, they don't live there. Also, they are the ones who have drawn in a bizarre boundary and claim part of our garden is theirs based on an unqualified surveyor. But, yes it must be our fault they have created a boundary dispute. Also our surveyor issued them directly a courteous letter merely informing them a pw notice is required and they flick it over to dodgy guy who returns a peevish letter.
Another part of my house (not party wall) will be within the 3 m of excavations as well if they do to line of junction, so a party wall notice would be required anyway. However, I wish this boundary issue to be faced head on.