Are you sure since we have had:There is no socket!
Ah I see why you say that.The cabal from the 13 amp socket to the mains has started to go black.
Okay I see your point that has cleared that up....but?It Is not connected to a 13Amp socket it is via dual pole 20Amp switch
on its own circuit back to the main board protected by a 16Amp MCB?
It Is the cabal from the 20Amp switch Thit is going a bit Black Do you think
It could be the 20amp socket that is at fault.
This is why I asked for photographs at the beginning.
I'm sure we can resolve the problem when the OP actually visits his daughters and photographs the problem rather than him and us second guessing as to what he is actually talking about.