It was Sunday 1 November 2020. The helicopter carrying his hush-hush VIP visitor was expected soon. Staring through the Chequers windows at the lawn where the unmarked Sea King would soon land, prime minister Boris Johnson could hardly believe what he was about to do.

Even by his standards, it had been a year of scrapes, of winging it and of close-run things that would have destroyed another leader. In the summer of 2019 he had defeated Jeremy Hunt by an unexpectedly narrow margin. A year ago he had led Britain out of the European Union without a deal.

He had been cheered to the echo at the Tory conference. The Brexit party had plummeted in the polls. But things had gone quickly wrong elsewhere. Was it really 12 months already since British lorry drivers fought daily running battles with French customs officers in Calais? How long it seemed since British Airways announced it was relocating to Paris and Barclays moved to Dublin. The mass layoffs following the S&P rating downgrade of Britain to BB status were especially traumatic.

When the Russian owner of the Belfast Freeport was arrested for fraud in the spring, even he thought his government was doomed. It was probably only the shock royal divorce in April, and the postponement of the general election, that had kept the show on the road this long. Just yesterday, two million people had marched through London in protest on the Brexit anniversary.

There was a knock on the door. “President von der Leyen is here, prime minister,” the official announced. “Welcome to my Eagle’s Nest,” boomed the prime minister cheerily. The European commission president did not smile. “Let us get down to business, Boris,” she began. “Tell me. Is this serious?” And she placed on the table a file headed “Top secret: UK government application to rejoin”.

Well, no, this isn’t entirely serious. Boris Johnson wears his principles more lightly than most. It is nevertheless highly improbable that a man who is currently clawing his way up the greasy pole would brazenly spurn his own cause in such a way. But who can say for sure? The pollster Peter Kellner made a plausible case this week that Johnson could end up calling a second referendum in order to retain power. As Kellner put it: “Changing his mind would be an addition to an already impressive list, not a break with any personal tradition of principled consistency.”

It is high time to get serious. Time, so to speak, to take back control. For the past six weeks, the biggest public issue facing this country has in effect been privatised to the Conservative party’s internal processes. The debate about Brexit options has spiralled into a netherworld of faith-based outcomes and fundamentalist beliefs, in which the candidates have made promises they cannot keep about processes they do not control.

Meanwhile the rest of us wait meekly for the outcome the Tory members demand. This is an act of collective negligence on the public’s part and an even more dangerous hijack of democracy by the minority of Tory MPs, led by Graham Brady, who successfully forced Theresa May out. Perhaps it will be reversed if Philip Hammond, David Gauke and perhaps even May herself can find a way of working across the House of Commons to stop the renewed drive towards a no-deal Brexit.

It is important to be clear about three things concerning a no-deal Brexit. First, a no-deal outcome on or before 31 October is now increasingly likely. Second, it will cause real damage to the country both in the short and the long term – damage about which the Brexiters are lying. And, third, it does not have public support; only 28% of all voters back no deal, and just 47% of Tory voters. Among under-25s, a mere 8% support no deal.

Rationally, it is political madness to desire no deal. But the leadership contest has narrowed the debate about options, so that the difference between Johnson and Jeremy Hunt on no deal is increasingly difficult to discern. Both candidates know they will not be able to negotiate a new deal. Both have boxed themselves into not seeking an extension. Neither is likely to expend limited political capital trying to finesse a negotiated Brexit through an already uncooperative parliament.

The contest has also used up a lot of precious time. The leadership election will be followed by a parliamentary recess, and in turn by the autumn conference season. With the Brussels EU leadership also in transition it becomes increasingly unrealistic to expect the two sides to find any new version of the withdrawal agreement and political declaration on which both can sign off, even if they both had the wish to do so. Which neither of them does.

This is made more difficult by the continuing levels of what Ivan Rogers, Britain’s former EU negotiator, recently called the “denial, delusion-mongering and deception” that still envelop the Brexit debate. It is inconceivable that the new prime minister will stand on the Downing Street doorstep later this month and renege on the things he has been saying during the contest by warning the public to prepare for difficult compromises. Yet without that, and without an extension beyond 31 October, no deal is not an option. It is automatic.

And that means that the UK will be in trouble, short-term or long – or both. Part of this is about tariffs. Mainly, though, it is about the ending of a preferential agreement on trading and commerce within the EU that has no replacement. No deal means no transitional period. This has instant negative consequences for checks on things such as industrial standards, financial regulation, phytosanitary provisions, aviation, road haulage, energy and tax. Why else, for instance, would a lifelong anti-EU politician such as the trade secretary, Liam Fox, now be so anxious to roll over existing EU free trade deals?

Speaking on Wednesday at an Institute for Government event in London, legal, business and government experts filled in some of the more immediate practical consequences. Planes will still fly and energy supplies will not be shut off. But the practicalities of trade in goods and, in particular, services (where the UK has a surplus) will alter decisively.

Some of this will be immediate. Calais will be a focal point as new checks apply and docks get clogged up. Other impacts will be more gradual as standards diverge and forms become more complicated. Both are likely. The free port idea floated by Johnson in Belfast this week would create more barriers, not fewer. The mitigation payments to farmers proposed by Hunt are illegal. Sorting out new arrangements, which will be on EU terms, could take years.

So forget about Wimbledon, the women’s football, the cricket and the summer holidays. Grasp instead that this is the month in which the Conservative party will decide to put modern Britain through the economic and political wringer simply in order to save its own skin from the Brexit party. No one voted for this, least of all in 2016. It would surely be better to remain than to have to rejoin.

• Martin Kettle is a Guardian columnist