is a big mess with building control and stuff, they wont keep records of every possible knocked wall, moved bathroom or state of consumer unit in every property.
they dont give a damn on their own, and not gonna bother unless someone will call them in to complain. they are here to make money selling rolls of red tapes
huge amount of dodgy cowboy work is going unnoticed by building control,
customers dont bother (it works), getting discovered by a proper spark after couple of years.
you can do EICR on it, based on whats up there now, not much more you can do.
if your client wants to call and inform them on his own, his business, his money, his trouble.