These square pin socket outlets are the same standard as those used today.
MK 2949 Double Socket Outlet
Surface mounted double socket outlet with separate backplate.
MK plastic single socket outlets
Various old MK single socket outlets with and without switches.
MK plastic double socket outlets
Various old MK double socket outlets with and without switches.
MK double socket outlet with surface mounting box
Older style MK double unswitched socket outlet complete with moulded plastic surface backbox, 4 fixing holes.
MEM socket outlets to BS1363
BS1363 socket outlets manufactured by MEM in the early 1970s.
AEI combined fused switch and single socket outlet
White moulded plastic socket outlet and switched fused connection unit combined on a single plate.
Although all of the sockets here have the same pin configuration as modern equivalents, those with four fixing holes cannot be used, as the 6 lug mounting boxes these fit onto are no longer made.