Because the main parties in Britain have completely alienated their voters after a series of revelations in The Daily Telegraph about MPs claiming expenses for all sorts of ridiculous things like "having their moat cleaned" (I kid you not). It's been a massive national crisis, loads of ministers have resigned and public confidence in the political system is at an all-time low. Lots of people have voted for the BNP as a protest vote, which seems fucking ridiculous to me, but they operate under this banner of not claiming expenses and all that, and it seems to have paid off for the racist, fascist evil fuckers...