This week, Labour headquarters has managed the extraordinary feat of handing Alastair Campbell the moral high ground. And Jeremy Corbyn has fumbled his way to a position where Remainers — about 90 per cent of party members according to a recent survey — must choose between abandoning their party or their beliefs.

His most senior colleagues — Emily Thornberry, John McDonnell, Diane Abbott — understand that. Jeremy Corbyn — whom I voted for, whom I like, and about whom I’ve co-written a supportive book — does not. So he must go, and go fast, while he can still be replaced by a leader from the left or the centre left, and the new spirit of hope and idealism that he has brought to the Labour Party can be preserved.

If he goes now, he will be remembered as the leader who ended the triangulation of the Blair years for at least a generation. If he hangs on, he will drive his own friends away, demoralise the left, pave the way for the Blairites to take over again, and allow the Conservatives to recover and win the next general election. Never underestimate the Conservative Party’s ability to escape its grossest errors — it overcame the 1956 Suez debacle to win the 1959 general election.

Every time I hear Corbyn take a deep breath and intone robotically: “Let me be quite clear. Our preference is for a general election…” I despair. It has become a mantra, a comforting reiteration of a “correct” political position, an escape from reality.

The Labour leader cannot deliver a general election, and he isn’t going to get one. There is only one thing that he can deliver, and that is a second EU referendum. He has had the power to deliver that since at least the end of last year. He could do it tomorrow. If the Labour frontbench unambiguously supported a People’s Vote, it could be secured.

If he withholds it, he will always be the man who facilitated a mean, reactionary, borderline racist Brexit, and refused to allow the people a say on it. That will be his legacy. If you want to oppose Brexit, you are now forced to fight both main political parties.

I feared it might come to this when I went on the anti-Brexit march in London in October last year. A group of young marchers next to me read what Corbyn tweeted that day, and exploded with anger. “Twenty years ago I was proud to join the campaign to extradite Pinochet for his crimes against the people of Chile,” he wrote while his supporters were marching against Brexit. “Today I am in Geneva meeting Michelle Bachelet who was imprisoned and tortured by Pinochet’s regime”. We didn’t deserve to have our leader go out of his way to tell us we didn’t matter.

He didn’t intend that, of course. What he wanted to do — what he has been struggling to do for months — was to say: there are more important things in the world than Brexit, such as climate change, and inequality. And of course, that’s true. But Brexit is what he has to deal with, right now. What dictates a politician’s agenda is, as Harold Macmillan imperishably remarked, “events, dear boy, events”.

And the big event right now is Brexit. Nothing else will get done until that’s dealt with.

There are two other factors preventing Corbyn from doing what must be done. First, he fears the backlash from what people are calling “Labour heartlands” if he does not do what Nigel Farage glibly demands and “deliver Brexit”, as though Brexit were a parcel. But he underestimates Labour voters — and Corbyn, if he plucked up the courage, is in a better position than anyone to take them along with him.

Second, Corbyn is stuck in the thinking that led him to oppose membership of the European Economic Community during the 1975 referendum. Then Corbyn (along with myself and many others on the left) opposed it because we saw the EEC as a capitalist club.

We have learned two things since then. One is that there is nothing in Labour’s 2017 general election manifesto that EU membership would prevent, but much that a future government could not do outside the EU. After Brexit, the UK would have to dance to the tune of whoever might be willing to buy its wares — the Americans, the Saudis, whoever. If Stalin’s dream of socialism in one country was ever achievable, it isn’t now.

The other lesson is that Europe is not holding Britain back from progressive policies; Britain is holding Europe back.

It was young idealists who made Corbyn’s election as leader possible, and it is they who are most passionate about stopping Brexit. This leader, loved (with good reason) by the angry and idealistic young, has hugged close to him the old, crabbed, bitter, sectarian left.

Francis Beckett is a journalist and the co-author of Jeremy Corbyn and the Strange Rebirth of Labour England (Biteback, 2018)