The Brexit vote didn’t create Remainers or Leavers, but it did give them names. On 12 September 2006, a little under ten years before the UK voted to leave the EU, the departing prime minister, Tony Blair, told the Trades Union Congress that politics in the 21st century would be dominated not by issues of left against right but of “open vs closed”: a question in part formed by how globalisation had changed people’s economic and social circumstances, but also by cultural and social issues.

That framing was flawed. Andrew Cooper – David Cameron’s pollster, who, like Blair, was firmly on the side of “open” – thought that it was unnecessarily pejorative, while one Blairite Labour MP complained that it was about as helpful as describing the new divides as between “respectable and loose”.

In his book The Road to Somewhere David Goodhart tried to finesse the division by describing the emerging divide between “Anywheres” – socially liberal, university educated, without strong community ties – and the socially conservative and locally rooted “Somewheres”. But Goodhart’s thesis achieved the double whammy of being pejorative and inaccurate: so-called Anywheres are, in fact, even more attached to their local areas than Somewheres.

Vince Cable perhaps got closest. He believed that British politics was increasingly shaped by what he called “the politics of identity”, in which questions of nationalism and liberty were becoming dominant in determining how people voted. When I spoke to Cable shortly before he announced his intention to stand down as Lib Dem leader, he made clear his frustration that economic issues were no longer the meat-and-drink of politics; but he was also keenly aware that the new politics of identity could advantage his party, as indeed it did in the local and European Parliament elections in 2019.

Cable and Blair both understood that while there are aspects of Brexit that are uniquely British, it is also part of a global trend. Whether it is successfully electing Emmanuel Macron in France or failing to keep the UK in the EU, the progressive coalition looks the same: an alliance in the big cities of the working class, graduates of all ages, ethnic minority voters, social liberals and the young.

And whether it is successfully electing Boris Johnson or failing to deliver a majority for Binyamin Netanyahu in Israel, the conservative coalition across the world looks increasingly similar: an alliance of the socially authoritarian, those without degrees, and the old. Across the political spectrum, well-informed MPs of all parties have observed the same change happening in their constituencies. A Labour MP told me in the run-up to the 2017 general election that the only good thing about Brexit was that it provided him with “an exact guide to which voters in my constituency can’t fucking stand Jeremy”. One Conservative MP credited their survival in 2017 to a campaign manager’s decision to stop canvassing voters who said they had voted Conservative in 2015, and instead to target everyone who had backed Leave in 2016.

Yet the Brexit effect has done more than give precise labels to either side of an existing political fissure – it has accelerated the widening of the gap. The transformation could be seen in 2015, in the Conservatives’ failure to retake the university city of Exeter, which until 1997 had been theirs for the best part of 100 years. In the same election, Ed Balls lost his Morley seat, which had elected Labour MPs since the party’s creation. The story of 2019 – and Labour’s present difficulty – is that there are more Morleys than Exeters in England.

The consequences of the 2016 Brexit vote will continue to define British politics long after we have left the EU: implementing it will be a project of decades not months. But it will endure in the same way that the global trend towards low interest rates has endured after the financial crisis: no one now describes the latest announcements from the Bank of England as “measures to fight the financial crisis”, though that is what they are.

And how will Britain’s Brexit tribes, particularly its ardent pro-Europeans, react to the United Kingdom’s exit from the EU?

For some Labour grandees, the precedent that comes to mind is the 2003 protest movement against the Iraq War. The marches, like the ones organised by the various pro-EU campaigns over recent years, mobilised many thousands but failed to prevent the New Labour government from being re-elected with a comfortable majority in 2005.

Yet ten years later, those frustrated marchers had changed sides twice over. First, they powered Nick Clegg’s Liberal Democrats into government as the junior partner in a Conservative-led coalition, with millions of people opposed to the Iraq War switching from Labour in 2005 and 2010. These switchers gave the Lib Dems a record number of seats and the balance of power in the Commons. Smaller but equally significant numbers of anti-Iraq War activists then joined Labour to vote for Jeremy Corbyn when he ran for the leadership in 2015.

Those two decisions continue to determine the course of our politics. The destruction of the Lib Dems after their five years in coalition opened the way for the Brexit referendum, and the defeat of Jeremy Corbyn in 2019 ensured that Brexit would happen. The respective parties have also been transformed by these events, yet no one could have predicted either of them the morning after the 2005 general election.

We can’t say with any certainty what effect the defeated pro-Europeans will have on British politics over the next ten years, but it would be foolish to say they will have none. While Brexit is a defeat for the “open”, it might yet come to be seen as the beginning of the end for the “closed”.