@cstross 1.a) The UK still had homes wired with the old round pin (2,5,15 amp) plugs until stupidly late.

A 2a round pin gave just enough energy to use a wee heating element to boil a cup of water.

For 13A plugs, the lowest available fuse was 3A so an old boilette could overheat for minutes before the fuse would blow....