I think the best definition of UKIP voters I've heard was said by (IIRC) a UKIP official (who is not named). The gist of it was: UKIP voters are people who have failed in life, and want someone to blame for it. This has always been a fertile recruiting area for extremist parties of all stamps, with the majority of members of such parties coming from lower-middle and working class backgrounds, doing low-skill and poorly paid jobs. They are convinced that something other than their own inadequacy is holding them back from a well-paid meaningful career and they have found a scapegoat. In time past it has been the underclass, Jews, Huguenots (yes, really), immigrants, and well, immigrants. Anyone but yourself. UKIP is just another round of this. Add a huge dash of old-fashioned (literally) conservatism (small c intended) and UKIP is just the latest bunch from a long line of narrow-minded bigotted Little Englanders.
However...
I do understand the frustration with the current politics and why people think "none of the above" should be a valid ballot option. Blair steered Labour away from poor people towards Tory Lite and support of Big Business. That leaves all the main three parties looking pretty much the same, with the feeling that no matter who you vote for you're going to get the same. Cameron is a Toff with no idea of real life, Glegg is a man who sold what little soul he has for power, and Milliband is so in hock to his spin doctors I simply have no idea what he wants or why. Politicians still haven't understood why the public have such contempt for them. So they just keep doing the same wrong thins and say that they are misunderstood. No, the problem is that we understand you very well, that's why we hate you.
That said, how a public-school educated stockbroker came to be seen as an "outsider" in all this is beyond me. It's even more mystifying that why people seem utterly unable to see through Boris Johnson's act.
On a similar note, another apparent quote attributed to UKIP is that they failed t get many votes inside the M25 because everyone is young, cultured and educated.

Perhaps the solution is to get rid of career politicians? People need a grounding in real life before they become politicians and lead a country that is full of "real life" people. There are some MP's and elected officials that are from normal backgrounds, unfortunately they are the minority. The majority get into politics at a young age and work their way up in the political arena without touching an outside job. It's one of the reason the House of Lords seems to be becoming more in touch with "common" person every day. The increase in Life peers with decades of experience in real life jobs bringing a semblance of sense into the proceedings.