
Ukip may no longer be a single-issue party, but it still has a defining cause: the withdrawal of Britain from the European Union. Twenty years after it was founded, David Cameron finally gave the party what it wanted last year: a promise of an in/out referendum.
The PM’s pledge created an awkward question for Nigel Farage: why, if you want a vote so badly, are you helping to stop the Tories (who have promised one), rather than Labour (who haven’t), winning the general election? As is well known, despite Farage’s protestations to the contrary, Ukip draws nearly half of its support from 2010 Conservative voters. The divided right, combined with a more unified left, could gift Ed Miliband the keys to Downing Street.