On Mon, 26 Apr 2021 19:34:31 +0100, ARW
wrote:

Went to a job today where the customer said the landing socket made a
fizzing noise when it was used.

Late 60's early 70's build and probably the original socket.

So I just swapped it. The customer then said "I'll go and get the
hairdrier as that the only thing that makes it fizz. Mind you it does
that to all the sockets in the house"

FFS You could see the sparks on the hairdrier flex when she turned it on.

I assume you told her all the sockets would need to be changed.