After a year of prevarication through 2012, David Cameron finally adopts the negotiating stance of Liam Fox, his former defence secretary and perhaps the most senior Eurosceptic on the backbenches.
The prime minister's call for an in-out referendum is a moment of truth for a pragmatic man assumed to be instinctively opposed to political risk.
Through the first half of 2012, Cameron had dodged and weaved in the face of a 100-strong letter from his backbenchers demanding he pass legislation in this parliament preparing for a referendum on membership in the next parliament.
He inadvertently lit the touchpaper with loosely chosen words at a press conference in Brussels on 29 June when he said: "The problem with an in-out referendum is it actually only gives people those two choices: you can either stay in with all the status quo, or you can get out. Most people in Britain, I think, want a government that stands up and fights for them in Europe, and gets the things we want in Europe, that changes some of the relationship we have in Europe."
Then in a landmark article on 30 June last year, Fox struck, arguing against an immediate in-out referendum, but saying: "I would like to see Britain negotiate a new relationship on the basis that, if we achieved it and our future relationship was economic rather than political, we would advocate acceptance in a referendum of this new dynamic ... For my own part, life outside the EU holds no terror".
Almost simultaneously, Cameron wrote: "As we get closer to the end point, we will need to consider how best to get the full-hearted support of the British people whether it is in a general election or in a referendum. For me the two words 'Europe' and 'referendum' can go together".
From that point, the Eurogenie was out the bottle.
Yet on 18 July, in a Daily Telegraph interview, Cameron insisted he did not want Britain ever to leave the EU. He said: "When I look at what is in our national interest we are not some country that looks in on ourself or retreats from the world. Britain's interest – trading a vast share of our GDP – is to be in those markets. Not just buying, selling, investing, receiving investment but also helping to write the rules. If we were outside, we would not be able to do that. It comes back to this – who are going to be the winning nations of the 21st century? If your vision of Britain was that we should just withdraw and become a sort of Greater Switzerland, that would be a complete denial of our national interests".
Yet if he was to achieve his aim of a new relationship with the EU, he had to inject credibility into his demand for that renegotiation, and the only way to do that is to suggest Britain could leave the EU if he does not get his way.
In his speech on Wednesday, he makes it crystal clear that following the negotiations he hopes to hold with his EU partners by the autumn of 2017, he will indeed be holding an in-out referendum. If he believes he has failed to renegotiate adequate terms, he will have to recommend Britain leaves the EU and seeks the status of a Greater Switzerland. Equally if he recommends the terms, and the British people reject them, he will have to say "very well, alone".
His plan has many pitfalls. His Lib Dem colleagues will have no hand in drafting the referendum legislation he intends to prepare before the election. Vince Cable, the business secretary, has already denounced Cameron's timing as disastrous. The sceptics will say "if not now, when ?" Cable will ask, why now in the midst of a recession?
British business could unfurl the flag of revolt. They might blame every job lost between now and his referendum on the foolishness of Cameron in putting party management before the national interest. More difficult, Angela Merkel and François Hollande may not oblige by operating to the timetable Cameron has set out. They could hold their treaty revision to strengthen Euro-governance after the German elections this autumn, but before Cameron is ready in 2017. They could deprive Cameron of a lever into a renegotiation by saying the changes can be made outside the EU institutions.
They could make the cold-hearted judgment that a strong Europe, including Britain, is an impossible fusion, and it is best the two sides to part more in sorrow than anger.
But he will argue Britain has to have this reckoning. If he does not renegotiate the terms of Britain's membership, the British people will demand departure, so this is the best way to secure Britain's membership. One thing is sure, he will hope he again secures the bond of trust with his own backbenchers, at least until they demand specifics on the powers he will repatriate.
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