Brexit has proved to be an equal-opportunity wrecking ball. It has not only damaged Britain, lowering the rate of growth and distracting attention from mortal threats such as obesity. It has damaged the party that hatched the scheme in the first place.

It may only be April, but Tim Bale’s The Conservative Party After Brexit: Turmoil and Transformation is surely destined to win the prize as the most depressing book of the year. It is a portrait of a once-great party in the grip of monomania, a chronicle of wasted time and a catalogue of missed opportunities. Read it and weep.

In 350 tightly packed pages, Bale, a professor of politics at Queen Mary University of London and a leading academic expert on the Conservative Party, reminds us of a succession of events that all but the ghoulish would prefer to forget: Theresa May coughing her way through her conference speech while assorted letters fell off the slogan “Building a country that works for everyone”; the Daily Mail dubbing British judges “enemies of the people”; Boris Johnson taking refuge in a walk-in fridge on a morning TV show in order to avoid hard questions; Brexiteers demanding, as 2019 turned into 2020, that “Big Ben must bong for Brexit”; Dominic Cummings, Johnson’s right-hand man, telling a select committee that his boss was “like a shopping trolley smashing from one side of the aisle to the other”; and Kwasi Kwarteng rushing back from a meeting in Washington to be sacked from the chancellorship by the Prime Minister, his best friend Liz Truss, as the British economy lay in ruins.

The post-Brexit Conservative Party has produced three of Britain’s worst-ever prime ministers. May is a dutiful civil servant — perhaps even a permanent secretary in a lowly department — who was hopelessly miscast as a senior politician. Johnson is a narcissist who always puts his own short-term interests before anything else, routinely lying to his colleagues and his country. He disappeared for long periods when he should have been in Downing Street — at one point he took a two-week break to try to finish a book on Shakespeare for which he had been given an advance of £500,000. Truss is a strangely robotic figure who cares only about two things: a highly simplified version of free-market economics and the day’s headlines.

These three were only the most conspicuous members of a Brexit menagerie. The Conservative Party might be compared to a mouldering British private school. David Cameron, who was prime minister from 2010 to 2016, tried to revive it by hiring some trendy new teachers and keeping the old lags hidden from prospective parents. However, Brexit, which he set loose with his referendum, gave the spotlight to a host of dim-bulbs, sleaze-hogs, popinjays, blowhards and incompetents. Among them, Brexit’s chief ideologue, the seemingly ubiquitous and certainly shameless oddity that is Jacob Rees-Mogg. These lags not only dominated the headlines during these years but also managed to turn a narrow victory (52 per cent to 48 per cent) into the hardest possible version of the European divorce.

The rise of the Brexit faction toxified British politics and created a culture of bullying and disrespect. I remember one red-faced hardliner boasting to me that they would “tear Theresa to pieces and leave body parts strewn around Westminster”. It thickened the air with plots and counterplots. No wonder the most talented younger MPs on the losing side left Westminster for a saner world. Quitters included such formidable talents as Rory Stewart and Nick Boles, while Suella Braverman and James Cleverley made it to the Cabinet and Chris Pincher made it to the Whips office despite a reputation for drunken groping. “The party is now led by a narrow sect who wouldn’t be out of place in a Muppet version of The Handmaid’s Tale”, one moderate Tory complained to Bale in the book.

The haemorrhaging of talent is part of a wider hollowing-out of the party. In its 1950s glory days, the Conservatives not only had some two million members but also a research department, an in-house training division, an army of agents and volunteers. It was so rooted in civil society that the Young Conservative Association was regarded as the best marriage market in the country.

The Brexit Conservative Party is a shell by comparison. With just 150,000 members, it is increasingly dependent on dodgy billionaires for its funding and highly paid consultants for its election fighting. Conservative business plans boast that potential funders are being presented with “an investment proposition rather than a donation proposition”. Dinner with leading Conservatives is shamelessly sold to the highest bidder in party events. At the 2022 Summer Ball fundraiser at the Victoria and Albert Hall, someone paid £120,000 (about $150,000) for dinner with the trio of Johnson, May and Cameron.

The party has contracted out its thinking to a collection of mysteriously funded think-tanks scattered around Westminster. Leadership contests are to some extent competitions among think-tanks to get “their” man or woman into the top job: the free-market Institute of Economic Affairs thought that it had won the lottery when Truss won the leadership ballot. The party also has a symbiotic relationship with what Bale calls “the party in the press” — The Daily Telegraph, the Daily Mail and, the weakest witch of the trio, the Daily Express, providing a chorus of headlines, leaks and editorials that have more to do with the political game than journalism. “At last! A true Tory budget,” the Mail roared about Truss’s “financial event” as global markets tanked and mortgage rates soared. The conservative press’s failure to provide proper scrutiny of Truss, a woman whose limitations were well known in Westminster, was particularly disgraceful.

The best political case for Brexit was that it would allow this hollowed-out party to reconnect with “the people”, just as the repeal of the Corn Laws had done in the 1840s and One Nation Conservatism did in the 1950s. Globalisation was increasingly dividing the country into highly educated “winners” who worked in the knowledge-intensive economy and “losers” who worked — or drew the dole — in the left-behind regions. The liberal elite made this worse by treating the left-behind as so much roadkill to be driven over by multicultural modernity. Brexit provided the key to realigning politics as well as satisfying the party’s demand for “sovereignty”.

The underlying story of Brexit is the brief success and long-term failure of this realignment. Johnson’s electoral triumph in 2019 saw large swaths of “left behind” England voting Tory for the first time. But this was more the result of working-class loathing of Labour Party leader Jeremy Corbyn — the quintessential middle-class leftie — and general exhaustion with Brexit.

The failure of realignment was partly the result of Johnson’s personal faults. Great Tory political magicians such as Robert Peel, Winston Churchill and Harold Macmillan were gifted with extraordinary powers of focus, hard work and, above all, seriousness — none of which Johnson possessed or even comprehended.

But deeper faults debilitated Johnson’s party.

First, the Brexiteers were divided down the middle on their reasons for leaving the European Union. Globalists such as Kwasi Kwarteng wanted to complete the free-trade revolution and turn Britain into one of the Asian tigers, while communitarians such as Michael Gove wanted to address the problems of people who had been left behind by globalisation. The post-Brexit Conservative Party thus stumbled from May’s “burning injustice” Toryism to Truss’s turbocharged Thatcherism with an intervening period of Johnson’s cakeism — that is, doing everything regardless of the cost.

The second shortcoming was the economic foolhardiness of the entire Brexit project. The 1846 repeal of the Corn Laws worked because it made the country richer and improved living standards by reducing the price of food. Welfare Toryism worked because the British economy, like that of the rest of Europe, was enjoying the benefits of Keynesianism. But Brexit significantly reduced Britain’s growth rate. The debate is now exclusively about who to blame for its failure — whether it is the “establishment” who, through resistance and subterfuge, turned a brilliant idea into a sham, or the inherent foolishness of withdrawing from a relatively open trading bloc.

In any decent morality tale, the Tories would be given a whipping in the next election for their Brexit mania. The Labour Party has now eliminated the strongest reason for voting Conservative by replacing Corbyn with Keir Starmer. And the economic case against Brexit continues to grow. But Bale rightly points out that a Tory defeat in 2024 is by no means a certainty.

The Tories have finally found a competent leader in the form of Rishi Sunak. The dream of levelling up is quietly being abandoned in the name of fiscal prudence. The party is putting the Brexit ghouls back into the attic where Cameron assigned them a decade ago. It is also framing the next election as a presidential one — between their tried-and-tested leader and Labour’s untried “nasal knight”.

Starmer faces serious problems with “woke” issues relating to national and sexual identity that unite the Tories and divide his party. He may also be making a mistake in harping on about Sunak’s wealth when many people think that being good with money is a positive quality in a leader.

The great irony about Brexit is that, rather than leading to a momentous realignment, it is leaving us with the political combatants we had in 2010. On one hand, the Tories pursuing a “Thatcherite” policy of cutting taxes (eventually) and holding down public spending; on the other, Labour, which wants to address social injustices but is nervous, despite the Tories’ record of breathtaking incompetence, of being seen as the profligate party.

Brexit has thus produced one of the strangest political revolutions in British history, driving a generation mad, damaging the economy, but leaving the fundamental battle lines almost unchanged.

• Adrian Wooldridge is the global business columnist for Bloomberg Opinion. A former writer at The Economist, he is author, most recently, of The Aristocracy of Talent: How Meritocracy Made the Modern World