Well, as the british use ring circuits with 32A fuses/breakers it isn't. So the plug fuse is there to protect both cord and appliance. Ring circuits are actually 2 2.5mm2 cables paralleled, but not run in parallel but forming a huge ring (for example the phase wire goes from the breaker to socket #1, from there to socket #2, socket #3,... and then finally back to the same breaker). A pretty complex setup and we've had quite some discussions about it in the past.
