However UKIP are an irrelevance, a political party with one MP (having lost 50% of their MPs at the general election) is simply not relevant in Westminster politics. They're as relevant as the Greens or Sinn Fein. What UKIP do have is great PR, naturally helped by the far-right presenter of the Today programme and ex-BBC political editor Nick "Tory President" Robinson, a man so far to the right he's happy to be involved in photo ops with Britain First.
As for Middle England, bear in mind that the Conservatives only won a majority due to the votes of around 900 people, even though Miliband was (according to the Blairites) a walking policy disaster. They are very fine margins.
Labour's vote collapsed in Scotland because the Scots don't want Tory and they don't want Diet Tory. UKIP and the Greens are gaining popularity because of anger at 30 years of Tory and Blairite policies; UKIP's supporters are not racist, they're just angry.