We have plenty of high days and anniversaries to choose from in the Brexit movement. Obviously, there will always be 23rd June – a date that has already been christened “Independence Day”. Then, so long as everything goes according to plan, we have 29th March to look forward to in 2019 and every year after that. I suspect in future decades these two dates will battle it out for supremacy as Brexit red letter days – the day the British people decided to leave the EU versus the day that the UK actually left the EU. And if we leave with a “transition” period to wade through, there will of course be the day on which that comes to an end as well. But what about 4th November, or more specifically 4th November 2009? The anniversary has just slipped by without being remarked upon yet again. But in my view it deserves to be remembered as a key staging post on the path to Brexit. What happened then? I hear you ask. Well, it was the day that David Cameron pulled the plug on his pledge to hold a referendum on the Lisbon Treaty, becoming the last major party leader to do so. Labour had originally pledged a referendum on the European Constitution, but bailed out of the pledge when that treaty was rejected elsewhere in the EU and repackaged as the Lisbon Treaty to be mis-sold by Labour as a mere “tidying-up exercise”. Nick Clegg on behalf of the Lib Dems had dumped a pledge to campaign for a referendum on Lisbon, arguing disingenuously for a “proper” In-Out referendum instead (the one referendum on the EU that pro-Brussels folks felt sure they would win back then). But Mr Cameron had given an unqualified and “cast-iron” guarantee of a referendum on Lisbon. To his credit, he spelled out his u-turn very clearly, telling a press conference: “The Lisbon Treaty has now been ratified by every one of the 27 member states of the EU and our campaign for a referendum on the Lisbon Treaty is therefore over.” A clearly uncomfortable Cameron insisted that a future Tory government would make sure that nothing like this could ever happen again – no further transfers of sovereignty to Brussels without a referendum. Shadow foreign secretary William Hague then became William Vague by muttering something ill-defined about how the Tories would not “let matters rest” as regards Lisbon, should they win the 2010 election. This was all regarded as a huge let down by me and many other Eurosceptics too. This was the same William Hague who as shadow foreign secretary had sat in the Daily Express editor’s office a few months previously (I was that paper’s chief political commentator) telling us in his flat Yorkshire vowels that blocking Lisbon was the “last chance” for the UK to retain its essential sovereignty. This was because of Lisbon’s terrifying self-amending properties, he added. It was a point that Mr Hague had relied on extensively during his campaign to force a referendum on the treaty. So a tame surrender coupled with a mysterious “we will not let matters rest” simply would not do. Either Mr Hague had been right that we must die in a ditch to block Lisbon and therefore was honour-bound to fight on, or he had been overstating his case to the point of insincerity. I suspect, incidentally, that the subsequent outcry from Eurosceptic voters and media was one of the things that served to convince David Cameron that the democratic mandate for Britain’s entanglement in the EU was in dire need of renewal. I do not suggest it was a clinching argument, for as Prime Minister he resisted the ensuing demands for an In-Out referendum for another three and a bit years. But it surely lodged there in his consciousness as a sign that the democratic elastic had been stretched to breaking point and that referendum deniers were henceforth skating on very thin ice. No, the main reason I would place 4th November 2009 as such a big moment in the battle for Brexit was because it was the day that the Conservative Party really began to lose its effective monopoly over Eurosceptic politics. It was clear to me and many others from that moment on that another political force would be required to pile on the pressure and indeed that a significant tranche of public opinion would give such a force a fair wind. There was no doubt as to what that new force would be either, because UKIP had already caused a minor sensation by coming second in the European Parliamentary elections that June (albeit on a 16.5% voteshare, some 11 points behind the victorious Tories). It would take until March 2011, at the Barnsley Central by-election, for UKIP’s potential as not just a protest party but a pressure party to really start showing with a second-place finish. And of course, Nigel Farage was the right man at the right time to personify the views of millions of profoundly Eurosceptic voters who, when presented with Mr Cameron’s coalition with Nick Clegg, smelt a rat. But I have no doubt that the Lisbon let down of Cameron and Hague was crucial. The pair had cleverly used anti-Brussels sentiment as a stick with which to beat Labour in their pursuit of power, but were unable to put it back in their political Pandora’s Box afterwards. I am glad to have lots of friends within the Conservative Party, some of whom are now bearing the huge responsibility of actually implementing Brexit. But for so long as the British media granted the Tories a monopoly of Eurosceptic voices (with the occasional comic turn from Dennis Skinner being the only permitted departure), the chances of securing Brexit were close to zero. The Tory genius for creating pragmatic fixes, muddling through and kicking things into the long grass would have simply carried on. As one Tory minister said to me at the time, after I had mentioned that I believed the time had come to break free of Brussels and that only this would resolve Tory splits on Europe: “It’s too difficult.” Well, it has been difficult and the difficulties are not over yet – but I am convinced we are going to get there. And nobody should underestimate the lasting impact that the debacle of the non-referendum over Lisbon had on British public opinion. A treaty that, in effect, created a country called Europe was imposed without consent. Little did any of the big beasts at Westminster know it at the time, but the elastic had already snapped.