Many years ago, I was outside the studio of the BBC’s Today programme waiting my turn to be interviewed about the latest sterling crisis. Alongside me were two gentlemen of a certain age who were keeping themselves to themselves and looked as though they would not hurt a fly. When my turn came, I said to the studio assistant: “As a matter of interest, who were those two gentlemen outside?” “Oh, them? They are the Militant Tendency.”

For younger readers, the Militant Tendency were an extreme leftwing group who came very close to capturing the Labour party. Not all of them were as harmless-looking as those two, and it is to the eternal credit of Neil Kinnock and Roy Hattersley that they fought them off.

Another important role was played by Denis Healey. Shortly before he died, the former Labour defence secretary and chancellor told me that he regarded beating Tony Benn to the post of deputy leader of the party in the early 1980s as one of his proudest achievements.

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Well, the success of Jeremy Corbyn’s Momentum movement, and the disturbing return of “deselection” of candidates not to the leadership’s liking, has revived unhappy memories of the early 80s among veteran Labour politicians and voters. Moreover, I have lost count of the people who are fed up with the Tories and wish Labour would get its act together in front of the open goal that is the May government’s craven approach to Brexit.

Talking of which, there is a marvellous summary of the state the May government has reached in the forthcoming Johnson’s Brexit Dictionary, by Harry Eyres and George Myerson. In the spirit of Dr Johnson’s famous dictionary – he of the dictum “patriotism is the last refuge of a scoundrel” – they define Brexit as “a negotiating process in which no real negotiation ever gets done; a promise of trade deals that somehow fail to materialise; the taking back of control leading to ever-intensifying chaos; or a play by Samuel Beckett in which the main character never arrives”.

I belong to a generation of men that is not easily moved to tears. If the situation were not so serious, all this stuff about “regulatory alignment” and “ambitious managed divergence” could easily reduce one to hysterical laughter. Our “negotiators” are intelligent men and women involved in the futile exercise of cherry-picking a barren tree – trying to have their cake and eat it when, oddly, we already possess the cake and are in danger of throwing away both it and the cherries.

I have said before that the prospect of Brexit has made us a laughing stock around the world. Does it not mean anything to Mrs May and the Brexiters who have captured her that the only two world leaders who approve of this gadarene rush to the cliff are Trump and Putin?

Some commentators have welcomed the way that Brexiters’ extreme demands over, for example, the “divorce bill”, have yielded to reality. But May still says we are leaving the customs union and the single market – the single market Kenneth Clarke regards as Margaret Thatcher’s greatest achievement. A recent Harvard survey of small- and medium-sized British businesses, conducted by Ed Balls, found that “the overwhelming majority” wished to stay in the customs union and “a large majority” wanted to remain in the single market.

Mention of Ed Balls – much missed on the political scene – brings us back to the Labour party. It is about time Labour’s present leaders, and their influential advisers in the shadows, recognised that the health service they affect to believe in is being severely damaged by the threat of Brexit and their own shilly-shallying over the issue.

Lord Kinnock, who fought so bravely against the extremist wing of the Labour party in the 1980s, has taken issue with Boris Johnson’s characteristically duplicitous claim that Brexit would be good news for the NHS. He says of Johnson: “He dodges the repeated reports from impeccable bodies that, since the referendum, the number of nurses coming to work in the NHS from the EU has fallen by 89% and the number leaving risen by 67%.” Moreover, the British Medical Association finds that a fifth of EU doctors working in the NHS plan to leave as a direct result of the prospect of Brexit. Kinnock makes no bones about it: Labour should be arguing for remaining in both the customs union and the single market.

We face the biggest crisis most of us have experienced in our lifetimes. At present, just as it was over Suez in 1956, the country is split down the middle. Suez was recognised by the Observer as a catastrophic mistake. Subsequently this was acknowledged by majority opinion. Do we really have to wait for realisation to dawn until after the deluge?

Labour leaders, please, for your country’s sake: wake up before it is too late!