The party is now regularly polling above 10 per cent of the vote in opinion surveys. Yet it need not score that high in the general election, or win a single seat, to do the Tories damage. Even if it sinks back to 6 per cent or 7 per cent, that will constitute in the region of two million votes in a tight election when Cameron needs every vote he can get. This new force on the Right, born of a split in the Tory tribe, could deliver victory by default to Ed Miliband, perhaps the most left-wing leader of the Labour party since Michael Foot. Before that come the European elections in May, ahead of which UKIP has talked up its chances of coming first or pushing the Conservatives into third place. 

In part to counter the charge that UKIP mainly takes votes from the Tories, and to rebut the claim that a vote for Farage will aid Miliband, the party has made much play of its assault on Labour. In last month's by-election in Wythenshawe and Sale East, UKIP came second ahead of the Tories and did eat into the Labour vote, although not very much. On a low turnout Labour got 55 per cent of the vote, UKIP 18 per cent and the Conservatives 14.5 per cent. The dramatic breakthrough against Labour Farage was seeking did not materialise.

UKIP's rise has been made possible by the fracturing of the old party system, of course. British elections in the decades after the war used to be relatively straightforward. There were two large parties and either Labour or the Tories could be sure of getting more than 40 per cent of the vote. Turnouts were high and the parties could rely on tribal allegiances rooted in class differences and social attitudes. Support for the two parties was widely spread geographically too. In 1955 the Unionist party and their Liberal Unionist and National Liberal allies even got more than 50 per cent of the vote, and half the seats, in of all places Scotland.

And then two-party British politics started to fall apart. The Liberal Party, which had suffered a near-death experience after the First World War, reappeared as a winner of by-elections after its shock defeat of the Conservatives at Orpington in 1962. In the early 1980s, the new Social Democratic Party joined with the Liberals to create the Alliance, and later the Liberal Democrats. Proper three-party politics emerged and once devolution was introduced the nationalist parties in Scotland and Wales had a new outlet. In 2010 Britain found itself with a coalition government for the first time since the Second World War. Even against a hugely unpopular Labour government led by Gordon Brown, in the aftermath of the worst economic crisis in seven decades, the Conservatives under David Cameron were incapable of scoring more than 36 per cent of the vote. It is in this unsettled climate that Nigel Farage and UKIP have prospered in recent years.  

So far Farage has also been lucky in his opponents. When David Cameron won the Tory leadership in 2005 he made a misguided decision that he would run the Conservative Party as though he did not need to worry about Tory traditionalists. Rather than securing his electoral base, and then building out to appeal to floating voters, the Cameroons attempted to define themselves as the opponents of core conservatives, in the expectation that if they emphasised their modernity they would attract so many moderates that it would not matter if some traditionalists stayed at home come polling day.

 

For a time this seemed to work. In the 2010 general election UKIP scored 3.1 per cent of the vote, more than 900,000 votes, and enough to cost the Tories seats in an election where they fell short of an overall majority. But it wasn't decisive, and the Tory leadership could still at that point convince itself that there was no requirement to take UKIP seriously.