It is not yet 28 months since the referendum, but it feels longer. The Britain that had not yet decided to leave the European Union feels eerily remote for a place we lived in so recently.

Political intensity can do that. The weeks after the vote were crammed with enough drama to fill months. Then Theresa May squeezed a self-sabotaging general election into the tight Brexit negotiating window. The era when governments understood the value of EU membership lies buried beneath a landslide of events. Recent history has become political archaeology.

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But it isn’t only the volume of news that has done this. The past is being chased out of view more aggressively than it might naturally recede. In the autumn of 2015, Tory MPs were still celebrating victory in an election won by David Cameron on a manifesto promising to “preserve the integrity of the single market”. How many MPs currently serving in Theresa May’s cabinet rejected that view? How many said that the single market was disposable because escape from the EU was a more valuable prize? The answer is none. Not one of May’s ministers – including those who speak of Brexit now as if they had yearned for it since childhood – saw fit to mention that feeling in public just three years ago.

Even on the back benches, “Eurosceptic” recently meant resistance to further European integration and a demand that powers exercised in Brussels be “repatriated”. The view that such a goal could only be achieved by quitting the club was explicitly held by about a dozen Tory MPs – including two who defected to Ukip in 2014. By referendum polling day, there was still not a majority of Conservative parliamentarians prepared to say that Brexit was a good idea.

People are allowed to change their minds, and the referendum result was pretty persuasive. It is normal for a seismic electoral event to reshape the political landscape. But it doesn’t have to eliminate memories of the way things stood before. Yet that is what the Brexiters seem determined to achieve.

A clique of Tory ultras have lately told Downing Street they might tolerate the UK staying in a shared customs space with the EU until 2022, two years beyond the transition period envisaged at present. This has been reported as a formal concession by the Brexiteers, although they have no official role in the process. The position of chair of the European Research Group, occupied by Jacob Rees-Mogg, has no constitutional value. It meant nothing two years ago. Somehow it has become the pulpit from which permissible boundaries of thought and deed are dictated to the prime minister.

The “concession” on a temporary customs union is meant to give May leeway to negotiate a Canada-style free trade agreement, and thereby to abandon her Chequers blueprint. Tory MPs are feeding out rope to be sure that any prospect of a softer Brexit is hanged. It is a proven system. Even the terminology has changed meaning since the referendum. A “hard” Brexit was once any deal that surrendered benefits of the single market. Now “hard” is used interchangeably with the idea of total rupture with no deal at all. “Soft” Brexit is used by many Tories to mean a deal unworthy of consideration by patriots.

That spectrum places the Canadian model as a middle way. But in 2016, the official leave campaign would not endorse such an obvious economic downgrade, ripping the UK out of frictionless commerce with its neighbours to borrow instead a template cut to suit a country 3,600 miles away.

Brexit hardliners are not really interested in the Canadian model, anyway. Their current position is just another twist of the ratchet, taking the whole conversation a notch further away from European integration. That has been the game all along: bullying by incremental demands, grinding away at Cameron until he offered a referendum, then the pantomime of waiting for his renegotiation, then the verdict that, alas, it was not good enough. Now it is the same with May: chivvying her towards the edge of a cliff while pretending to be interested in bridges.

It happens so insidiously that it can be hard to keep one’s bearings. Not long ago, comparisons of the EU to the Soviet Union were the stuff of sweaty diatribes on Ukip web forums. Now they appear in speeches by a foreign secretary who voted remain. That is not an ordinary conversion to Brexit. It is symptomatic of a project to pretend that Britain never had pro-EU Conservatives or a pro-European political tradition. It is the systematic erasure of remain from the national story. The new Tory orthodoxy casts EU membership as an aberration, an alien thing imposed by a few “citizens of nowhere” on a captive people who prayed in secret for deliverance, then rose up to take back control.

That isn’t how 48% of voters, 16.1 million people, saw it. But it takes an effort to keep hold of the memory. The past two years have felt like a vast exercise in gaslighting – the method of psychological coercion that involves subtly undermining people’s confidence in what is real until they begin to question their own judgment. Thus have the parameters of sanity in the debate shifted. The norms have moved so far that any deal starts to look like a victory for common sense over extremism. But that is only because today’s political maps don’t even mark the spot where realistic accounts of Britain’s European interests used to appear.

May is relying on that disorientation when urging MPs to back her in the Commons. She will offer something she calls moderate and declare its adoption vital for the national interest, measured on a scale that only shows degrees of folly and national self-harm. And then the idea is that we put the whole sorry business behind us, let EU membership fade from our minds. Let the wind and dust erode our memories until the past is barely recognisable: a ruin, somewhere the forgotten tribe of Remainia once lived. But the problem is, prime minister, we’re still here.

• Rafael Behr is a Guardian columnist