All today's political parties in Britain started small, the Tories, the Lib-Dems, Labour. The Tories were given that label by the Whigs, then in power and the precursors of the Liberal Party, as a slight. it was a comparison with a rowdy Irish family. Labour was introduced to give the working masses a voice, and became a voice for the Middle Classes under Neil Kinnock and 'Teflon' Tony Blair. The Lib-Dems (for the benefit of non-UK nationals short for Liberal Democrats) are a shift away from the Liberals of the 80's.
So there are a lot of disenchanted Tories, Socialists and Liberals who see Nigel Farage and UKIP as a 'stick to beat sense into the mainstream parties'.
It's doubtful they will take over from the mainstream, and each party warns that a vote for UKIP will bring in the opposition. We'll see how it turns out next May, but by-elections are there to tell the government to pull their socks up.
Will Diddly-David listen, or will he go the way of ex-leaders and provide more coffee table fillers?