When wiring was being upgraded here in the 1960s and 1970s there were instances where people tried to camaflauge old wiring by replacing the old BS546 sockets with BS1363 or replacing crumbling old VDE sockets with newer ones but left all of the wiring in situ. This particularly happened when people were selling a house. It became common practice for any surveyor to remove a few random samples of sockets and light switches and check the wiring behind them.
it was potentially a Leathal fire hazard! You'd find thin rubber cables connected to a 13A socket which had replaced a 2 or 5Amp light socket and could even have been wired into the lighting circuits.
