A lot of somewhat dubious surveyors keep an eye on planning documents that are being filed and then contact the neighbours with dire warnings of the consequences of not getting a separate surveyor for the party wall (that surveyor obviously being them).
I was a bit pissed when my previous neighbours went down that route, particularly as their surveyor cost shitloads more than mine, but in the end I thought it was fair enough.
Had this the other week - other neighbour (not the one with the wanky note) are building a shed at the end of the garden. Party Wall surveyor telling us it'll affect us (it won't) and to get in touch.
A lot of somewhat dubious surveyors keep an eye on planning documents that are being filed and then contact the neighbours with dire warnings of the consequences of not getting a separate surveyor for the party wall (that surveyor obviously being them).
I was a bit pissed when my previous neighbours went down that route, particularly as their surveyor cost shitloads more than mine, but in the end I thought it was fair enough.