<< I'd go for somebody like Edward VIII myself- he managed to spark a consitutional crisis through being a selfish idiot, and was altogether a little too cosy for comfort with Hitler aftwerwards. Or, one of the trade union leaders of the 70's- Jakc Jones, "Red Robbo" or similar. The amount of damage any of those three did to Britain was far greater then Mosley, who although a bete noire was never a threat. >>
Clement Atlee would be a good pick, too and a geurnsey goes to Snatcher 'Hong Kong' Snatcher, whose son and members of whose cabinet profited obscenely from her craven surrender into serfdom and slavery of Once-FRee-British Hong Kong's seven and a half million Once FRee British Hong Kong Citizens and their Trillions of Dollars of wealth ranks up there with Churchill's Gallipoli campaign and surrender of Singapore and Churchill's and Roosevelt's 1945 surrender of all of Eastern Europe's subsequent slaves to the gulags and to Stalin's Soviets' surrogate slaughterers.
But Mosley was more an eccentric dickhead than ever a threat and if the only measure of a society was its treatment of its eccentrics, Britain, rather than having degenerated into a squalidly-fascissocialistic offshore satellite state of the other Europeons' neo-Soviet, would have ever been up there with the best of nations.
It's always nice to see your temperate and original contributions- when I read the section about the 'squalidly-fascissocialistic offshore satellite state' (do you have that phrase permenently on your clipboard ready for pasting by the way?) I find that it helps to imagine that you suffer from a lisp. Hours of fun, you must try it!