That's the excuse all the main parties are coming out with too
Hilarious!
It's true. It's the same reason the Lib Dems did well in the last general election.
A half decently organised / funded party that get given an opportunity in the media, grasp it well and run with it to see a sharp increase in support. People are always anti-the government in power. The wounds form labour are still too deep and Ed Miliband is not charismatic enough to paper over the cracks (even though leaders shouldn't actually matter that much in real terms!)
With the three main ones crossed off, and with a charismatic leader UKIP have had a sharp rise, that's fact. Also, at times of austerity the Right tend to see a rise, so all these results are to be expected.
However, this doesn't change the fact that they have a severe lack of policies and that i'm sure the big parties / press have a very strong smear campaign building for the next year.
Half of the UKIP vote - floating voters, will quite quickly distance themselves from them when they are made explicitly aware of others associated with the party and things that have happened in the past.
People have voted as a protest this year and fair enough, but those that are chanting UKIP UKIP UKIP thinking it's the start of a revolution will be bitterly disappointing next year m'fraid.