The horror of that spectre, together with a residual but no longer fully functioning appetite for power, is what keeps it together. Laying down her Brexit plan at Chequers last week, Theresa May, like John Major on June 22, 1995, challenged her critics to put up or shut up.

A formal leadership challenge may come, but it was the moment she turned around to face down her critics within.

There is a common thread through those 23 years to Chequers, from the garden in Downing Street, where Major threw down the gauntlet to his tormentors by resigning as party leader and promptly standing again.

It ties together ideology, rancour and bloody ambition. Frustrated, harried and spectacularly losing a critical division by eight votes on the Maastricht Treaty in a House of Commons where he had a majority of 18, Major in an infamous outburst off camera but on-microphone called his critics “bastards”.

It was the making of him. One David Davis MP was the whip in Major’s government responsible for European legislation and eventually mustered the votes to get it through.

In his autobiography, Major, who was from a working-class background, looked back on the

antipathy of the British imperial tradition towards the nascent European Economic Community in the 1950s.

Sentiment moved somewhat under Ted Heath, but Tory Britain faced across the Atlantic to the United States, and not across the Channel to Europe.

Ironically, as he pointed out, Margaret Thatcher through the Single European Act of 1985 conceded the most dramatic advance of decision-making by voting majorities, for a share of pooled sovereignty.

It delivered on her ambition of a truly free market in goods and services. It added the “ism” to Thatcher and globalised what she stood for.

Maastricht and what came after was within the framework of the Treaty of Rome, and historically deepened by the Single European Act.

But Thatcher afterwards, in the full flowering of her imperial phase, recoiled from the consequences.

The lady, mortally wounded by the disloyalty of colleagues she led to three election victories, by 1992 was sitting in her room in the House of Lords, where out of the sight of David Davis, conservative MPs were ferried to her. She urged them to stand up for Britain and vote against Maastricht.

What is at stake now in Brexit and the potential election of Jeremy Corbyn, is the first sea change in British politics since Thatcher’s election in 1979. She fundamentally disrupted the post-war social order of the welfare state, and if more in legend than in fact, created a liberal open economy.

The EU through the Single European Act was a pillar of that. But shared sovereignty and the opaque processes of Brussels were culturally a Tower of Babel and politically a surrender of Britain’s once imperial dignity she would not wear.

In 1997 the Tories were weary and put out of power after 18 years. It was not, however, a major change. Arguably it was no change at all. New Labour was Thatcherism set to pop music.

Gordon Brown, David Cameron and Theresa May, like Tony Blair, adapted to but never disrupted Thatcher’s economic settlement. The first credible challenge is from Corbyn now. He, like Brexit, is in the offing.

Boris Johnson in 2018.

Leaving the European Union, will profoundly and perhaps permanently, dis-unify the United Kingdom.

This is the irony of the twaddle pedalled by wannabe Winstons like Boris Johnson. For context, it is worth recalling the resignation of the last British foreign secretary on an issue of principle, Anthony Eden in 1938 over Chamberlain’s policy of appeasement. Specifically, it was about recognising Mussolini’s invasion of Abyssinia.

It is hard to think a comparison could be made either of the characters involved, or the circumstances. But ultimately Borris may be politically a far more important player than Eden. Both had qualities projected onto them they completely lacked.

Eden, however, was ultimately incapable of rabble-rousing and that might be the best compliment that can be paid to him. Borris is the best in British politics since Oswald Mosley. His resignation letter is an appalling work of genius.

The appalling part, of betrayal, connivance and opportunism, is well documented. The genius part is still to be proven.

But the phrases in that letter, like Elgar’s music in another era, captures completely the sentiments of Brexit Britain. The rank and file of the Conservative Party are Brexit to the core.

They are Blimpish and Blighty to the roots of their remaining grey hairs. Boris is the Bonaparte nightmare of a corporal with a field marshal’s baton in his knapsack.

When Mrs May’s compromises begin, which they must, the fact of Borris’s resignation, not the deceit of it, may count for more.

Two facts stand out. Firstly, however, whenever happens, the Chequers plan won’t pass muster in Brussels.

Secondly, there is no majority for any one form of Brexit in the House of Commons. There will come a moment as Cromwell said to the Long Parliament and as Leo Amery repeated to Neville Chamberlain in 1940, “You have sat too long here for any good you have been doing. Depart, I say, and let us have done with you. In the name of God, go.”

If Conservative MPs are to go to the country and face the threat of a Jeremy Corbyn they would once have scoffed at, in desperation they might yet turn to the Boris. In that danger, the dull men in well-pressed suits who are the alternative may be no choice at all.

But whatever his personal fortunes, he has written the legend of Brexit: “Brexit should be about opportunity and hope…That dream is dying, suffocated by needless self-doubt.” As Boris himself might say, that’s bollocks. But that’s not the point.

Theresa May.

Corbyn is unthinkable without Brexit. He is the expression and continuation of its nihilism. His masterly adaptation of principle to politics shows steel and ambition.

That ambition is to be prime minister. He may potentially enter 10 Downing Street just at the once in a generation moment, he can make fundamental change. But then, the world is different from 1979. Globalisation is a fact. The possibility of socialism in one country, always remote, appears more so now.

Then, there is a fundamental dilemma, of which Brexit is part symptom and part cause. In a globalised economy, and a deepening interdependence of things technically from cars to the IT systems that control them, to the basic means of modern communications, what is the role and the capacity of the nation state? Simply put, though Thatcher railed against it, it is a smaller one.

Boris is the Bonaparte nightmare of a corporal with a field marshal’s baton in his knapsack