In an earlier post, I looked at the huge increase in immigration during the New Labour years, which facilitated the rise of Ukip. As a footnote to that, I feel I should point out that there are limits to the power even of this issue. I think Ukip enjoyed its greatest moment at the elections to the European parliament in May last year. It won't get that good again.
Indeed, I said as much at the time when I predicted on the day of the elections that Ukip had now reached its peak number of voters. 'If you don't vote Ukip this time,' I wrote, 'you're unlikely to do so at a general election next year.'
On that basis, I predicted that the party might reach a 14 per cent share of the vote in this general election, adding: 'And even that's being optimistic.' That was before the results had been announced. In retrospect, I think it was indeed a touch optimistic: according to the Poll of Polls on May2015.com, Ukip currently stand at 12.7 per cent.
In a subsequent blog post last May, I then put a figure on the number of votes Ukip would attract in this year's election: 2.5 million people. I think I'll stick with that.