David Cameron may have finished off the Tories - but he had no choice Fortunately, we don't have to guess - because all this has been tried before, in very similar circumstances, and for near identical reasons. Back in 1972, Harold Wilson, leader of the Labour opposition, faced a similar dilemma to the one Mr Cameron does now. His party was horribly at odds over Europe. The majority of Labour MPs (like most Tory MPs today) were fiercely opposed to Europe, partly for old-fashioned reasons of national sovereignty, but mainly because they regarded Brussels as the headquarters of a sinister capitalist plot to exploit the workers. Meanwhile, Roy Jenkins led a pro-European rump. As a result the Labour Party was all but ungovernable and there seemed no way it could fight the forthcoming general election on a united manifesto. Most unusually, it was Tony Benn (then approximately halfway along his journey from respectable technocrat to Left-wing fanatic) who produced the solution. He came up with a characteristically radical and shocking proposition, an affront to the British tradition of parliamentary democracy: a referendum. Wilson bought the idea and included in Labour's election manifesto a pledge that the party would renegotiate the British terms of entry to the Common Market, and then put the result to the people. The ruse worked: the party went quiet. Arch-Europeans like Jenkins cheerfully campaigned side by side with antis like Michael Foot. Labour narrowly won an election victory in February 1974, and from that moment Wilson embarked on a year of tortuous negotiations with the European Commission. His incoming government set out seven areas where it wanted change in Britain's favour. These included reforms to the Common Agricultural Policy, the introduction of some restraint on Brussels spending, a promise that Britain would never be forced into the single currency, and no harmonisation of VAT across national boundaries. Prime Minister Wilson achieved virtually nothing in his renegotiation. The Brussels budget and the CAP carried on their majestic way. Even he had to admit this: "We do not pretend, and never have pretended, that we got everything we wanted in these negotiations." But Wilson, a notoriously devious politician, maintained: "We did get big and significant improvements on the previous terms." It was on the basis of these illusory "big and significant improvements" that Labour recommended that Britain should remain inside the European Economic Community. Chaos ensued. As the stock market collapsed to its lowest level since the Blitz, and amid talk of a military coup to be headed by Lord Mountbatten, several Cabinet ministers (including Tony Benn and Peter Shore) announced that they would join the No campaign against their government colleagues. Others sat it out. Labour did regroup for a few years after the referendum was won by the Yes camp. Yet in retrospect it is easy to see that those early splits over Europe formed the basis of the party's civil wars of the early Eighties and the secession of the SDP. History is about to repeat itself. If David Cameron is lucky, his referendum wheeze will quieten matters for a time. All the indications suggest that we then face another version of the mid-Seventies. The British Government will set out its key objectives for negotiations. Some of these will be met in part, but the majority will not be met at all. Prime Minister Cameron, who fundamentally does not like to rock the boat, will present these European concessions to the British people as a victory and lead the Yes campaign. But many ministers and others will disagree. Here are some who can be expected to join the No camp and campaign alongside Nigel Farage's Ukip: Owen Paterson, Iain Duncan Smith, John Redwood, Liam Fox and very possibly Michael Gove. I would expect half the parliamentary party to join the No campaign, as well as the majority of Tory activists. The long-term effect of this - as with Labour in the Seventies - will be a formal Conservative split. It is impossible to envisage circumstances where a referendum over Europe would not do grave damage to the party. It would be unfair to assert, however, that the Prime Minister has made a mistake. William Hague's bomb was likely to go off anyway, and in recent months the Conservative Party has become more and more ungovernable. At bottom, yesterday's speech was a grubby piece of party management, the kind of thing Harold Wilson would have been proud of, and not necessarily any the worse for that. Mr Cameron's referendum pledge has pleased his backbenchers, shot the Ukip fox, befuddled the Liberal Democrats, embarrassed Ed Miliband's Labour and made Conservative election prospects more cheerful. There are almost five years until he has to deliver on his promise. Anything might happen in that time - and, besides, the future is another country.