In British politics, the unspoken rules are: what you see is what you get, and what you don’t see is generally more of the same. Tony Blair said the private sector was preferable to the public sector and his government shovelled money in the direction of Richard Branson; Margaret Thatcher said there’s no such thing as society and proceeded to smash society. They may have hidden stuff – but it was just a more extreme version of the stuff they did in public.

By contrast, the Johnson administration has been characterised, from its first seconds, by duplicity. Only once you understand that, can you grasp the audacity of the coup Boris Johnson, and his elite friends, have just pulled off.

His desired outcome is fairly clear: to leave the EU on 31 October “in name only” – leaving Britain inside the single market but outside the political institutions. There would be no need for a backstop, and no need for special legislation concerning EU nationals because freedom of movement would continue. As a sweetener, Britain would carry on paying into the EU’s coffers. We know that’s his preference because – on the rare occasions journalists have managed to ask him a question – that’s what he replied: “a standstill … until such time as we have completed our free trade agreement”.

If you strip this of all the emotion, it’s not a bad plan. Theresa May’s plan not only handed Brussels sovereignty over Britain in return for temporary access, it handed the power to set the terms of the halfway house, and the conditions for leaving it, to Brussels too. Johnson’s intent – if he were honest enough to say it – is to give Brussels complete sovereignty over the UK for up to five years as the price for complete freedom thereafter.

Instead of a close relationship with the EU, which is what all the major parties promised at the last election, there will then be a hostile one, with Britain dragged in the wake of an isolationist and protectionist US, much as every superyacht drags a dinghy.

To get there, however, he has to run a regime of artificial crisis. He has to make the risk of no deal appear so great that, against all its previous utterances, the EU scraps the withdrawal agreement and, in the space of a few weeks, signs a “fag packet” deal that allows the UK to keep all economic relationships at a standstill, while ending all political ones.

What you see, over the next few weeks, will not be what you are intended to get. The mismatch between what Johnson and Dominic Cummings say in Downing Street, and what Chloe Westley tweets on their behalf, will be absolute. It will be a regime of lying. They will stir up English nationalist bile, exonerate violent misogynists, flaunt privilege and, with the help of the mainstream media, otherise any politician, journalist or public figure who calls their lying into question.

Stopping them will not be easy, because – like Trump – they are prepared to dishonour all the unwritten rules and conventions that a modern constitution consists of. The exoneration of Conservative MP Mark Field, who violently grabbed a female protestor, is the microcosm that tells the story. Johnson regards the investigation into this display of casual violence as “a matter for the previous prime minister”. So, by implication, was Priti Patel’s freelance diplomacy in Israel. So was the expenses fraud committed by Brecon MP Chris Davies, who Johnson texted at 5:45am on his first day in office, after his constituents forced him into a by-election. So, presumably, was Westley’s tweet in support of far-right activist Anne Marie Waters.

The broadcast media, which fell so easily into the Nicholas Witchell style as Boris met the Queen, will be of little use. Just as the US liberal media refuses to say “Trump makes racist remark”, so ours will refuse to say “the Prime Minister lied today…”. Sure, the presenters and editors at the BBC and ITN will turn up to numerous worthy media conferences bemoaning fake news and populism, and forever tutting about Jeremy Corbyn, but they will fail this simplest of tests.

The complication is that defeating Johnson’s plan A in parliament only triggers his plan B – which is a real no-deal, with the chaotic meltdown of public services, a slump in sterling and serial bankruptcies among small businesses. Johnson’s calculation is that, should this by accident occur, it will be all the easier to win an election – the people versus parliament – especially as the pro-Remain parties are divided.

Yet it’s clear that Johnson can be defeated. One of the reasons governments tend to operate on “what you see is what you get” is that even that is hard: getting civil servants, advisers, business and media chums lined up around a single policy objective has been beyond the range of talents for many people in the new cabinet. Running a regime of systemic lying is hard, even if parliament is prorogued.

Johnson’s entire career has been constructed around buffoonish ambiguity, and it’s a trope you often find within the ruling class in exactly those places where morality and truth are not required. Because the system itself is supposed to be clean and straight.

And here, beyond all the calculations and manouverings between the parties and factions among the left and the progressive centre, is where our advantage lies. The British self-image remains, fundamentally, as set out by Noel Coward in his wartime family drama, This Happy Breed. In it, a character tells his grandson that the British were able to build an empire that survived so long because they “struggled all these hundreds of years to get decency and justice and freedom for ourselves”.

Johnson’s will be a regime of indecency, injustice and unfreedom – for these are the ideals people like Patel, Sajid Javid and Esther McVey live by.

It may be that Johnson is defeated in parliament, or in an election, or simply by a revolt of the decent people still left among Tory MPs. But, ultimately, what will defeat him is this mismatch between most people’s desire for truth and decency and the reality of a government based on lies and manipulation.

The association of truth with good and lies with evil is hardwired into our society through thousands of years of religion, reinforced by four centuries of rationalism. Say what you like about Corbyn, but I fancy the chances of anybody who is prepared to be straight and moral with the British people, in the face of a systematic amoralist and a liar.