hat Boris Johnson once described as a failure of statecraft now looms over Downing Street. As Britain prepares to end normal commercial contact with the rest of Europe, we must try to understand the endgame that is passing through the prime minister’s mind. Johnson has egotistically ensured that the final resolution rests with him. Only a major last-minute concession by him personally can avert the economic calamity of a no-deal Brexit. In the Commons this week, he seemed to be pumping up the anti-EU rhetoric, revelling in the cheers from what must be a tiny band of no-deal enthusiasts. Can he now find the guts to back down? Throughout the negotiations, Britain’s team has misjudged the weakness of its position. All that was required was a continuation treaty for the UK to trade freely with its 27 neighbours, as it had done for 40 years. At stake was 43% of the UK’s total export trade; by contrast, according to 2016 figures, the UK accounts for only 16% of the EU’s exports market. It was never conceivable that the UK could dictate the terms of a treaty. The issue had nothing to do with democracy or sovereignty, only with the terms on which each side wished to do business. The Conservatives politicised the negotiations at every turn. Constantly asserting that Britain would be better off doing deals with the rest of the world invited the EU to adopt a tougher position at the end of the game than at the start. Yet the prospect of a trade deal that could compensate for Britain’s lost trade with the EU was always illusory. Johnson often cites Canada’s deal with the EU, but Canada’s equivalent of the EU is the US. Until the last minute, the only remaining trouble seemed to be over fish, where Britain’s fishing fleet has certainly been at a disadvantage. Both sides appeared close to reaching an agreement. But Britain has made this area an issue of principle, and duly invited retaliatory intransigence from France, which promises to veto any deal that sacrifices the demand for continued EU fishing access to British waters. This was inept. The same obstinacy appears to have impeded progress on the tedious issue of a level playing field. That this should have become a deal-breaker makes me wonder if grown-up diplomats were ever at the table. Everyone has an interest in fair trade; a weakened Britain even more so than a strong Europe. If the UK wishes to continue trading as it does now, it’s obvious that it must accept a continuity of common standards. If competition is not fair, trading partners will not tolerate it. How fairness is regulated is essentially a technical matter. In this case Britain has left the EU and voluntarily withdrawn from a role in setting the regulations. That was the price of Brexit. As of last week, the EU’s Michel Barnier proposed that, should Britain change its laws in a manner the EU felt damaged competition, the EU could impose one-sided “lightning” tariffs on UK goods. But from the start, the EU was determined not to make it seem advantageous for member states to leave. British negotiators should have known that. Throughout the negotiations it has been difficult to tell what Johnson’s strategy is, other than extracting publicity from each turn of events. Negotiations were subject to a barrage of grandstanding from London, in addition to ministers’ bad faith assertions, since withdrawn, that they were willing to break international law over the Northern Ireland protocol. In the case of the level playing field, Johnson was reduced to demanding the “right” for the UK to subsidise export industries, undercutting cross-Channel competition. This was as diplomatically implausible as it was ideologically bizarre. A Tory should welcome a regulated free market, not seek freedom to corrupt one. If no deal is reached by this Sunday, the cost to jobs and economic growth will be immense. Police will lose access to vital EU data. British farmers could be crippled with tariffs. Scientific cooperation will be impeded. Britons will find travel with the continent complicated and expensive. Healthcare abroad will no longer be free. According to one 2018 estimate, no deal would deliver the British economy a savage 7.7% loss of income over the next 10 years – now in addition to the costs of the pandemic. The clock of half a century of pan-European cooperation would be turned back decades. None of this was in Johnson’s scant Brexit manifesto, and it is no secret why. Had the halfway house of remaining in Europe’s single market been adopted, this fiasco could have been avoided. No one in the Brexit camp can begin to explain why the lunacy of no deal is to anyone’s gain. Only Johnson can stop it, and stop it he must. • Simon Jenkins is a Guardian columnist