We’ll come out, deal or no deal, on 31 October. That’s the spirit! We’ve got to have the courage to tell the people of this country we can do it if we really want to.” So says Boris Johnson in his jaunty launch video, all blind faith that he alone can leap the Brexit impasse when he is anointed prime minister (odds now 11/10). Where’s the democratic legitimacy? We the people are mere dumbfounded onlookers at the insolence of this coup, not “taking back control” but letting him seize it.

Soon he will saunter into No 10 with no plans and an impossible promise to leave the EU on 31 October

Already his “no deal” talk is doing real damage. UK manufacturing shrank last month at the fastest rate since the referendum, with export orders at a three-year low. Construction figures fell their fastest for a year due to “ongoing political and economic uncertainty” as “a fragile dreariness descended on the sector”, according to the Chartered Institute of Procurement and Supply. Retail sales fell by 2.7% in May, the worst drop since records began, though consumer spending is what has kept the economy afloat. Wednesday’s service sector figures are unlikely to lift the gloom.

Make UK, representing manufacturers employing 2.7 million people, blames Brexit chaos, pointing at cavalier candidates calling for a no-deal Brexit. Even “moderate” Jeremy Hunt supports no deal, though “with a heavy heart”. Never mind his heart, look at the real world consequences of these wildly irresponsible would-be leaders. “There is a link between people standing up and saying no deal is acceptable and people losing their jobs as a direct result,” warns Make UK’s chief executive Stephen Phipson. Reckless Brexiters call it Project Fear, but he says: “It’s not theoretical or hypothetical scaremongering.” It’s happening now.

Play Video 2:09 'We're out, deal or no deal': Boris Johnson's official campaign video

Talking to manufacturers large and small in the past few days, I have heard them describe in granular detail what no deal means. Gordon Ellis and Co, with a £5m turnover, makes healthcare aids and employs 100 people in Castle Donington, Leicestershire. They export 20% to the EU: if there’s no deal, trading on WTO rules adds a 6% tariff. Even worse, they need an EU CE quality kitemark to sell in Europe, requiring an EU-authorised representative and file holder, which could cost tens of thousands of euros. Companies say that in the absence of a CE mark but with some newly invented UK kitemark instead, the world is less likely to buy British. Managing director Fiona Ellis-Winkfield wrote to her MP warning that no deal will add £90,000 costs and cause job losses. She told him some employees “voted Brexit, but they will happily tell you they didn’t vote for a ‘no deal’ and a risk to their jobs”, and that as a Tory voter, “I will not be able to vote Tory in the next election should there be a no deal”. What response? Her plea fell on deaf ears: her MP is Andrew Bridgen, extreme no dealer.

Schneider Electric, with a £1bn turnover and 4,500 employees, tells the same story, expecting a 10% hit and the same tariff and kitemark problems. Their greatest risk is the Brexit effect halting big national construction projects. Forget any talk of an “industrial strategy” to invest in infrastructure for declining areas.

The fall of superstar fund manager Neil Woodford is an interesting Brexit result, as his once £15bn fund slams its doors to anyone trying to escape. After the referendum he bragged he would defy gloomy Brexit forecasts. The FT reported “he sees Brexit as a buying opportunity, he has been building stakes in UK banks, retailers and housebuilders – which he believes are discounted for economic Armageddon – as he refuses to ‘chase the zeitgeist’”. But Brexit caught up with him.

Brexit is not the cause of Britain’s political breakdown. It’s a symptom | Gary Younge Read more

Johnson’s video, neutralising his past “Fuck business” remark, pledges to “support our wealth creators and business sector because otherwise we’re not going to have the dosh to invest and cut some taxes”.

Soon he will saunter into No 10 with no plans and a promise to leave the EU on 31 October that is bound to be blocked by the limbo parliament. The EU will not shift on Ireland’s backstop, as the DUP menaces for more bribes. The sound of crashing economic indices will ring in his ears, with no money in the Treasury, no trade agreements except Donald Trump’s sinister “once the UK gets rid of the shackles” offer. Terrified of an election, his party dare not bring him down, but a referendum will look grim. His lifelong bid for glory will be rewarded with a historic role as the last Conservative prime minister. From journalist purveyor of Euro-myth poison through to seizing power without consent, he will be architect of his party’s demise. These reckless last-of-the-Tories deserve their fate.

• Polly Toynbee is a Guardian columnist