The Brexit slogan “Take back control” was always a lie. Boris Johnson, in a long boast about his so-called achievements in the Sunday Express yesterday, wrote that he “took back control of our borders”. Perhaps he should have visited the M20 in Dover, where thousands of immobile lorries are stacked up, and repeated this claim to their drivers. Under the EU, Britain’s borders were an issue negotiated with its neighbours. Under Brexit, the border at Dover is now controlled by France – and there is not a thing Britain can do about it. When we left the EU we lost all control. The movement of people, goods and services across borders is always a matter of mutual advantage, of negotiation, of give and take. The prosperity of the British Isles since the Industrial Revolution has been rooted in ever-freer trade with the outside world. Membership of the EU made Britain’s products competitive, its banks rich and its labour market open to all talents. This gain reached its climax when in 1986 Margaret Thatcher signed the Single European Act, initiating a quarter-century of sustained growth. This era ended in 2019 with Johnson’s hard Brexit. The government’s own statistics estimate that it will reduce Britain’s growth by as much as 4%. The Tories have gone from being a free market party to a protectionist one, and it will cost the UK dear. Tory leadership candidates, as they spout their pseudo-Thatcherite cliches, lack the guts to admit this. Watching television over the weekend, I could sense the speech bubbles rising over Dover: “Why did no one say Brexit meant this?” More than 40% of British trade was with Europe in 2017 and in every sector controls have increased and bureaucracy blossomed. Not a day passes without news of a 50-page form to transport a single piano. British scientists cannot collaborate with European ones. Trade in perishables has fallen dramatically. Much-vaunted “deals with the rest of the world” are few and far between and cannot begin to compensate. What feels like daily news of chronic labour shortages – including estimates of up to 60,000 roles in health and social care alone – is met with plummeting numbers of EU workers in Britain. Meanwhile, Whitehall officials must mimic Soviet commissars in guessing national quotas for fruit-pickers and abattoir butchers. This must be why a majority of public opinion, according to one Statista poll, now accepts that Brexit was a mistake, and is surely entitled to a hearing. While many of the present frictions might have been negotiated away under a softer Brexit – Brussels was initially prepared for this – Johnson’s orgy of anti-EU hostility simply ignored any downside. If Britain lost its EU labour supply, he suggested the hospitality, farming, health and care sectors should simply pay British workers more. He never planned for this. The implied cost to the public sector was never budgeted for, or its inflationary implications considered. Much of this may quieten down. A future government may succeed in detoxifying Brexit and seek advantage in joining at least Europe’s single market. For the present, every time Johnson boasts of taking back control, his picture should flash up over the M20 with the caption: “Blame him.” Simon Jenkins is a Guardian columnist