I’ll be outside tomorrow investigating!
I do know that the sparking wires were just to standard phone sockets but do lead back to the active master.
again thanks for all your help!
Basically, if you just want to use the master socket for the hub, make sure the external cable connects to the A and B terminals at the rear of the socket. Any other cables connected to terminals 2&5 on the removable faceplate can be disconnected.
Just be wary of any unconventional wiring utilising extension wiring to 'backfeed' the master from an extension.