David Cameron’s offer of a referendum on whether Britain should leave the EU many years from now, in the event of a Conservative majority government, pending substantial renegotiations with the EU in advance, is so stuffed full of hypotheticals that it’s a wonder how much time we’re all devoting to it (yes, I know that includes me in writing this column). But amid all the uncertainties, one thing that can be said with reasonable confidence is that Cameron has reduced his chances of being Prime Minister after the next General Election.

This point was made with customary force by Steve Richards yesterday. As Steve – typically well briefed – put it: “Because of Cameron’s position on Europe, I do not believe the Lib Dems could form another coalition with the Conservatives”. Remember the Tories have a vast electoral mountain to climb to get a majority. Never mind the current polls; it’s their unpopularity with women voters, ethnic minorities, the north, and the public sector (before austerity has really kicked in) that means their chances are minimal.

Scars of history

So put together the low chances of a Tory majority, and the lower chances of Lib Dems forming another coalition with the Tories, and you can see why Steve may be right. But I think you can go further still. Look to history and I think you can say the other reason David Cameron may not be Prime Minister is that he may – may – not have a Conservative Party to lead. At least not in its current form.

Every Conservative leader since Margaret Thatcher has been confronted with a Tory split over Europe, and eventually succumbed to it. Cameron is no different. This week Tory MPs roared with approval at his arrival in the Commons chamber. But what happens when, in private meetings, he tells them that he is in favour of Britain staying in the EU? He will quickly discover that Liam Fox, Douglas Carswell, John Redwood and David Davis want out – as do many others, each carrying precious votes and support with them.

Hasn’t Cameron – repeating the mistakes of Harold Wilson, Labour’s then leader, in 1972 – just formalised the beginning of a new phase in a decades-long Tory civil war over Europe? The difference is this time the latter have an attractive, well-funded, plausible home. It is called Ukip.

The progressive century

For most of the 20th century, it was the British centre-left that was split. The result was conservative dominance. Now a Prime Minister who wanted his party to “stop banging on about Europe” has offered Labour and the Lib Dems the chance to be reconciled and deliver a progressive century.

Whether they do so depends, to a disconcerting degree, on Ed Miliband and Nick Clegg burying their differences. Their relationship is now the most important in British politics. Recent reports suggest a thaw. It is so clearly in both Labour and Lib Dem interests to get together, and dance on common ground, that both parties should be clearing diaries to arrange dinner, wives and all, between their leaders. If they’re after a discreet venue, I live in Highbury and cook a mean tagine.