Familiarity is a distorting prism. All too easily the extraordinary becomes the unremarkable, the aberrant the commonplace. This is what has happened in Britain following the referendum decision to leave the EU. The attempt to wrench the nation out of its own continent has triggered a national nervous breakdown. Only the British cannot see it.

Open plotting against an enfeebled prime minister, civil war in the cabinet, a ruling Conservative party riven by faction, a Labour opposition led by a life-long admirer of Fidel Castro, parliament imprisoned by the referendum result, paralysis at the heart of government — all have become the stuff of everyday politics. Britain was once a sturdy, stable democracy. Anger and acrimony are the new normal, as likely to elicit a weary shrug as incredulity.

Historians will scratch their heads in wonder. These are truly extraordinary times. Britain is upending the economic and foreign policies that have set its national course for half a century. Nothing in modern peacetime matches the upheaval. The impact on the nation’s prosperity, security and role in international affairs will be felt for a generation and beyond. Unwrapping decades of integration is a task of huge complexity.

And yet Theresa May, the prime minister, dare not set out her preferred course for a post-Brexit settlement lest she be toppled by her own Tory MPs. Instead she pleads with Germany’s Angela Merkel to tell her what Berlin might offer in terms of a future relationship. The humiliation is excruciating.

With each step back from the melee, the picture becomes all the more incredible. Most MPs in the House of Commons consider Brexit an act of folly. They will vote against their judgment because the referendum, with its narrow majority for leave, has been invested with an absurd, almost mystical status. Let no one dare question “the will of the people”. With the odd, honourable exception, Tory and Labour pro-Europeans seem inclined to let Britain sink rather than make common cause across party lines. A nation that calls itself the mother of parliaments has somehow mislaid the meaning of representative democracy.

They [MPs] will vote against their judgment because the referendum, with its narrow majority for leave, has been invested with an absurd, almost mystical status

Brexit is an act of protectionism promulgated by English nationalists who inexplicably style themselves free-marketeers. Every study produced in Whitehall suggests departure from the single market will leave Britain poorer and less able to promote its interests overseas. Throwing up barriers across the Channel will weaken its voice across the Atlantic.

Only this week Mrs May sought unsuccessfully to suppress an official analysis showing the alternatives to EU membership will reduce growth and cut living standards. Tory Brexiters are unmoved. The cabinet Brexiter Michael Gove sets the intellectual tone when he pours scorn on the insights of experts.

Baffled historians will search in vain to find a single official in the high echelons of Whitehall — from the cabinet secretary down — who thinks Brexit is anything less than a catastrophe. But what of “global Britain”, the bold Elizabethan future imagined by the Brexiters? Alas, the historians will discover, the vision amounted to no more than rhetorical flatulence on the part of Boris Johnson, the foreign secretary.

Where all this leads, it is impossible to say. Mr Johnson, whose calculated mendacity is matched only by inflated self-regard, is determined Mrs May should be ousted. Personal ambition burns more brightly here than any convictions. The foreign secretary has no project or purpose in mind. He wants to be prime minister because, well, he wants to be prime minister. Parallels with US president Donald Trump are not far-fetched.

Mrs May could survive. But to what end? Without the confidence of her cabinet and deprived of a majority in the House of Commons by an ill-judged general election, Mrs May has neither the wit nor the authority to reach a sensible agreement with the EU27. Most MPs would back a “soft” Brexit, leaving Britain’s economy closely connected to Europe. Mrs May feels threatened by the English nationalists. Her strategy, if you could call it that, is to leave all the serious decisions until after Britain’s departure from the EU in March 2019.

In other circumstances Her Majesty’s loyal opposition might offer a counterpoint of stability. Instead Labour is led by Jeremy Corbyn, a 1970s hardline socialist who sees the EU as a capitalist conspiracy. Mr Corbyn may launch opportunistic strikes against the government but shows no enthusiasm for a close relationship with the EU27.

As for the voters, some may have changed their minds. Polls suggest the 52:48 per cent tally in favour of Leave would be reversed in a second referendum. Maybe. But these numbers are well within the margin for error. Why anyway should people take a different view before they have seen the deal on offer from Britain’s erstwhile partners and, pace Mr Gove, have weighed the evidence as to the likely effect on living standards?

If there is a slim hope that Britain can emerge wounded rather than broken, it lies in the possibility that things will get still worse in the short term. Mendacity, chaos and division could end in complete paralysis — with parliament failing to agree on any form of Brexit. If Britain does remain part of the EU after all this, it will be because, in its present state, it is simply incapable of leaving.

philip.stephens@ft.com