“It was Game of Thrones,” says George Osborne. The former Tory chancellor of the exchequer was talking about the fateful referendum 10 years ago, on June 23, 2016, on whether the United Kingdom should remain in or leave the European Union. Or rather, he was talking about one man in particular, and Osborne’s comparison was just right. For Boris Johnson, the referendum—in fact, all of politics, even all of life itself—was a game, although also an opportunity. The one thing it wasn’t to Johnson was a serious matter with grave implications for his country.Just how grave we can now see. Every warning about the malign consequences of leaving the EU has been justified. This is not the place for detailed economic analysis with statistics and tables, but just to take one example, and a detached transatlantic view, a paper published last year by American academic economists, chiefly at Stanford, compares the U.K.’s performance since the referendum with those of similar countries and reckons that the U.K. economy is 8 percent smaller than it would have been had we remained inside the EU. Our particular problems are a grossly inflated financial sector that produces a disproportionate amount of tax revenue but is particularly vulnerable to a crisis such as that of 2008, along with a larger postindustrial economy characterized by low education, low skills, low investment, low wages, low growth, and low productivity. These wouldn’t have been cured merely by remaining in the EU, but they have been patently aggravated by leaving.One obvious and undeniable consequence of the referendum has been political chaos. In the 40 years from 1976 to 2016, there were in all six British prime ministers. In the decade since the referendum, there have also been six. And soon there will be a seventh, with Sir Keir Starmer having thrown in the towel on Monday. He will presumably be replaced by Andy Burnham in a kind of coup. It’s yet another in a series of coups, a Labour premier kicked out as a succession of Conservative premiers— Theresa May, Boris Johnson, Liz Truss—were before him. This latest change cannot be justified by any serious belief in Burnham, whose political résumé is far from stellar—a member of Parliament for 15 years (when he loyally and repeatedly voted for Tony Blair’s criminal and catastrophic invasion of Iraq); a minister for a few years; an unsuccessful candidate for the Labour leadership not once but twice; and then mayor of Greater Manchester, where his achievements were genuine but quite modest, such as improving the bus and railway services. His only real selling proposition is that he’s not Starmer.And all of this stems from that fateful day 10 years ago. The referendum campaign remains one of the most unpleasant experiences of my life. To be clear, I say that as a Remainer, but not just because of that. One might sometimes feel like the American pol years ago who said, after losing an election, “The people have spoken, God damn them,” but one can accept defeat after a fair fight. But the Brexit referendum was anything but fair. It was a squalid exercise in demagoguery or plain mendacity. A riveting two-part BBC program, Brexit: A Very British Civil War, is the latest in the long line of brilliant documentaries produced by Norma Percy, an American adornment of British broadcasting. Her oeuvre includes important additions to our knowledge of the bloody disintegration of Yugoslavia and conflicts in the Middle East, but my favorite may be the Watergate series, made 20 years after Richard Nixon’s resignation, which is not least a comic masterpiece, as all the old burglars and bunglers revisit, and try to explain away, their malfeasance.There is a certain similarity in the Brexit program, even if there’s nothing at all funny about the consequences. It all came about because of the internal politics of the Conservative Party. Once upon a time it was the Tories who were the Europhiles. One Tory prime minister, Harold Macmillan, made the first attempt to join what was then the European Economic Community, or Common Market, in 1963, before he was blackballed by Charles de Gaulle. Another, Edward Heath, did join in 1973. And as is often forgotten, it was one more Tory, Margaret Thatcher (yes!), who ratified the Single European Act in 1986 establishing the single market. After her fall, a group of Tory M.P.s began a guerrilla campaign against further European integration, and they harried John Major during his troubled prime ministership from 1990 to 1997. When David Cameron became Conservative leader of the opposition in 2005, he told his party to “stop banging on about Europe,” but his words went quite unheeded.