The fuse in the plug was chosen to protect wiring on ring circuits. They could also have put the fuse in the wall socket. After all, they already put switches o

The fuse in the plug was chosen to protect wiring on ring circuits. They could also have put the fuse in the wall socket. After all, they already put switches on them. Of course then you would have to go with the screw-in fuse design that was used in circuit breakers back then, instead of the fuse design in UK plugs.