Has the country ever been so badly governed as by this out‑of‑control Conservative party? The moving remembrance on Sunday of the end of the first world war reminds us of a time when an even worse government accidentally plunged the country into a far greater cataclysm. But short of war, the folly, incompetence, ignorance, obstinacy, stupidity and delusions of the party that brought us to this crisis are unparalleled.

This Brexit vandalism in the middle of a cripplingly long recession is brought to us by a party that has taken leave of its senses. The world looks on aghast, amused, amazed and maybe pleased to see our strutting on the world stage punctured by our own absurdity, as our influence ebbs away.

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Theresa May chose to ride the tiger of her party instead of protecting the interests of her country. Blundering at every point, she made a very bad situation worse. Why trigger article 50 with no plan, no preparation, no strategy? Why promise undeliverable red lines, without warning of inevitable compromise? Why agree a meagre 21-month transition, when a complex trade deal takes years?

May has wasted 28 months, with the great boulders of Ireland and frictionless borders still where they were on day one. Nothing has changed, in her immortal words, with only weeks left before agreement must be made for all 28 countries to ratify. All that has happened is the crystallising of Brexit’s great impossibilities.

There may yet be no deal, as the European Union stands where it always did on its rules. When Michael Gove, serial Brexit referendum dissembler, said Britain “held all the cards”, we find the UK’s 66 million citizens have rather less heft than the rest of the EU’s 442 million. If May does get her deal, the fractious cabinet hardly needs Boris Johnson’s call for “mutiny”. This ship of fools running and ruining the country will calculate their personal advantage, as, inexplicably, most vie for the poisoned cup of leadership. But if they do grudgingly nod it through, what then?

This is where Labour holds sway, a rare moment for a hungry opposition. Headcounters say May needs at least 30 Labour MPs to defect – which is why the Labour leader’s words matter. What was Jeremy Corbyn doing, denying in an interview that Brexit could ever be stopped? Did he want it stopped? “Not really. No,” he replied as if he barely cared about the crucial issue of our era. Labour shadow ministers scurried everywhere on Monday to damp down alarm in the party, unsure whether to say he misspoke, he didn’t mean it, he was not really concentrating – anything to deny his 1970s Brexit instincts had erupted.

But if you can ignore the leader’s one-day blunder, Labour has positioned itself perfectly in its official conference vote. Uniting all sides, they will vote – Corbyn, too – against any deal that fails its six tests, all based on the Brexiters’ own original unachievable promises. Corbyn needs to rally all the MPs he can to follow him into that No lobby.

May needs to attract some 30 Labour defectors: a while back she might have won over so-called “Blairites”, but Tony Blair himself begs them to vote against her “worst of all worlds” deal. Northern MPs from leave towns might have given her their votes – but on second thoughts, a vote to keep the Tories in power feels a greater betrayal of their constituents. Labour headcounters reckon that May will get the eight or so usual suspects: 15 at most.

YouGov’s latest poll shows most Labour voters in leave seats now want a final say: May’s Brexit is light years from what they were promised. This week the eloquent reasoning of the resigning Tory minister Jo Johnson sent a great wind of common sense blowing through the Commons.

Facebook Twitter Pinterest People take part in the People’s Vote march in London last month. Photograph: Xinhua/Barcroft Images

If May’s deal is voted down, says the influential backbencher John Whittingdale, “it’s almost impossible to see how she can continue”. If the party does decapitate her, voters will regard this as no time for the civil war of a Tory leadership election. The dwindling and aged party membership would probably select a Brexiteer to send back to renegotiate with a deeply unwilling EU. The new leader may stand on a “clean Brexit” platform, proudly walking the no-deal plank, as the party splits irreparably.

But don’t imagine even such mayhem necessarily yields Labour the general election it wants. In mid-schism, the Tories would certainly lose: so when her hotheaded MPs think a little harder, they may after all prefer to cling on to Theresa May.

Furious parliamentary debate on all options – May’s deal, Canada, Norway and more – may well not yield a majority for any of them. But there will certainly be an enormous Commons majority ready to vote against “no deal”. Keir Starmer is dead right to call May’s bluff. Her threat that it’s her deal or no deal is a “political hoax”. She will try her damnedest to terrify MPs, but the headcounters know that no deal is now unconscionable to most MPs.

Oh, the irony that it was Brexiteers who demanded public preparations for no deal to frighten the EU – but instead terrified most of their MPs. This weekend the army chief of staff said “we stand ready”. Cobra meetings are planned, ships readied to transport generators to Northern Ireland. Hospitals, schools and prisons are told to stockpile food, while businesses will soon spend millions on chillers and warehouses for food and medicines.

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The Food and Drink Federation (FDF) is outspoken in its warnings of gaps on the shelves: 40% of our food is imported, most from the EU. When the former Brexit secretary David Davis says no-deal trading on World Trade Organization rules will cause just “a hiccup”, he hopes voters don’t know these rules mean tariffs of 63% on butter, 53% on wheat and 43% on cheddar, according to the FDF – while our sheep farmers, exporting 90% of their lamb to the EU, face a 60% tariff (in fact, 55% of their incomes are European subsidy). We would crash out overnight from satellite, security, atomic, medical and countless other agencies. These things MPs now know and fear.

A Commons vote will expose the no-dealers for the paltry force they are: Jacob Rees-Mogg/Johnson/Davis Brextremists are only paper tigers. As if waking from a nightmare, people will wonder how these few fanatics seized hold of party and country with bamboozling promises to take everything from the EU but give nothing back.

Yet May’s deal looks barely better – and nakedly worse than what we have. That’s why the Brexiteers are afraid of testing the will of the people now. Amid all this chaos, if MPs can agree on no one’s deal, then parliament will have to abdicate to the people. Give them the final say: bad deal, no deal – or stay with the good deal we have already.

• Polly Toynbee is a Guardian columnist