Select, behead, repeat. That’s now the playbook of Britain’s governing Conservative Party, as they cycle through one sacrificial lamb after another to immolate on the altar of Brexit. What a strange turn of events. This is, after all, the country whose self-conceit was to run stable, pragmatic governments while others lost their heads around it. Instead, today, as one American journalist put it, Britain resembles a banana republic.

However, perhaps what Britain resembles most is that trouble-making friend you had in high school – that one who was always up to trying those things you thought might be fun but didn’t have the guts to do, and who was left carrying the can as you experienced vicarious thrills. Because while Britain faces a challenge all Western countries are grappling with, it has approached it with the thrill-seeking recklessness others dare only whisper about.

Britain, like all Western countries, is in decline. Back at the turn of this century, the developed Organisation for Economic Co-operation and Development (OECD) countries accounted for four-fifths of global economic output. Today, they’re down to three-fifths, with that number falling fast. Needless to say, the adjustment is proving painful.

Even if most people first experienced relative decline only after the 2008 financial crisis, it started decades ago. In retrospect, it was inevitable. Essentially, the West got too rich. For two centuries, the global economy had been heavily tilted in its favour, with the net flow of resources working their way back into the economies of the Western world. Thus, whereas in 1800 per capita incomes across the world’s countries were more or less equal, by 1950, average incomes in Western countries were running about 30 times greater than those in the Third World.

That’s when the final wave of decolonisation brought an end to Europe’s empires. Curiously, though, independence didn’t initially bring economic emancipation to the Third World. Instead, as dozens of new countries turned inwards to build self-sufficient economies, Western countries exploited their technological edge to pull further away. Sure, India and Kenya were building their own factories, but they were importing Western machines to operate them. And so, over the first half-century of independence, most developing countries fell further behind. In 2000, average incomes in the West had reached some 50 times those in the ex-colonies.

Nevertheless, as globalisation advanced and international trade rose, that gap grew unsustainable. Sooner or later, Western firms were going to realise that they could produce products more cheaply in the developing world than at home, and would start looking for opportunities at the frontier of the world economy. By the 1960s, as countries like Korea and Singapore began to orient themselves towards specialised manufacturing for export markets, that process slowly began. It then accelerated late in the century, as neoliberal reforms across the developing world prised open markets that had hitherto been closed.

Come the turn of the millennium, therefore, for the first time in two centuries, the net flow of global capital stopped heading towards the core of the global economy, and began going to the periphery. Average annual growth rates in the developing world now surpass those of the developed countries by some margin. The West has not stopped growing. But like an ageing runner facing a youthful challenger, the huge lead it started out with is being closed.

One would think that if it managed its finances well, a country whose economy is still growing needn’t face a bleak future. Unfortunately, during the fat times after the Second World War, Western countries didn’t always manage their finances so well. In particular, the citizens of the West voted themselves hefty bonuses, from cradle-to-grave welfare and generous pensions, assuming that future growth rates would always match those of what was, in reality, an exceptional time. So when growth slowed, governments had to start cutting some programmes to maintain others. Austerity set in.

In addition, the advent of pensions and public healthcare meant that people who previously had produced large families to support themselves in their old age, no longer needed to. As family size declined, the pool of workers in the economy dropped below what was needed to support this ageing population. In and of itself this wasn’t a problem. There were still plenty of workers available in the world, and Western countries needed only import them from the developing world, where populations were still booming. They did just this in the decades after the war.

The problem was, for those people who’d come of age in rich, monochromatic societies, this wasn’t what they’d bargained for. They wanted to both eat and have their cake, the cake being a society which looked and functioned as it always had, without all these dark-skinned newcomers. And there were always politicians only too happy to sell them that very product – the ways of the past but the incomes of the future.

Britain probably felt this transition more acutely than most. For after the war, it didn’t just lose clout in world affairs, it lost an empire. By the 1960s, as immigrants came into Britain from its former colonies, racist politicians began fanning the resulting discomfort. In 1968, the Conservative politician Enoch Powell gave an infamous speech in which he warned black people would soon rule over white people in the United Kingdom.

Black Britons still scratch their heads at that one. But while Powell was roundly denounced by the political establishment, he was eagerly received at the margins. One of his greatest admirers, a mere lad at the time of his speech, went on to become one of contemporary Britain’s most effective politicians: Nigel Farage.

By then, the British establishment had largely resigned itself to the loss of its empire and had turned its gaze eastwards, to Europe. In 1973, Britain joined what would later become the European Union. For men like Farage, this was the great betrayal. To them, Britain had turned itself from overlord of the world to a secondary partner in a union. And so, as they pined for the lost greatness of the past, nativist politicians like Farage began blaming Britain’s relative decline on – wait for it – the immigrants who had kept the economy going as its labour force declined.

The rest is history. As Farage’s star grew, support for the Conservative Party waned. When he became prime minister, David Cameron had the clever idea that if he called the Eurosceptics’ bluff and held a referendum on leaving the European Union, Farage’s threat would fizzle out. Mr Cameron still thinks that was a clever idea.

He had made the fatal mistake of drafting a referendum question so vague – in a nutshell, do you want to leave the European Union? – that it was left to campaigners to define what that actually meant. Different audiences got a different story from different people. As a result, while there has never been a majority in Britain for any one model of Brexit, whether hard or soft or a mix of the two, campaigners like Farage and the Tory politician Boris Johnson were able to sell a one-size-fits-all Brexit. The devil would lie in its details, but the details were left for another day.

When Theresa May took over from the ill-fated Cameron as prime minister, she could have enumerated those devils. She could have pointed to the slender majority for Brexit, the lack of consensus on what it meant, and thus proposed a compromise that tried to give everyone a little bit of the pie. But she was not that kind of a leader. Rather, she took Farage’s bait and said “Brexit means Brexit.’ She also perpetuated the false claim made by Boris Johnson that Brexit would be all gain, no pain. So when she finally produced the inevitable compromise that pleased nobody, her critics cried treason. That was the end of her.

Britain’s Tories now find themselves trapped in a death spiral. With Farage’s new Brexit party having scored big gains at their expense in this past weekend’s European elections, they are hearing the siren-song of people like Johnson, till offering pie-in-the-sky, unicorn Brexits. The Tories are already tearing themselves apart over who will succeed May. But when, as Cameron and May did, that eventual leader’s pledges to deliver Brexit crash into the reality of what can actually be obtained, he or she will, in turn, hear the cries of treason. Barring a leader with the charisma and vision to free the party from this spiral with some plain talking, the Tories will probably march towards oblivion, the only remaining question is whether they manage to take Britain down with them.

Meanwhile, the rest of Europe, which just a few years ago had egged Britain on as it tried the exciting and risky stunt of leaving Europe, has turned away, leaving the country to be frog-marched alone to the principal’s office. Europe’s other populist parties, watching as Britain hastens its decline, have decided not to try that stunt after all.

Even Britons, themselves humbled and shaken, may yet choose quietly to eat their humble pie, and remain. DM

John Rapley is a Visiting Fellow at the Johannesburg Institute for Advanced Study (JIAS). He is also a political economist at the University of Cambridge, and author of Twilight of the Money Gods (Simon and Schuster, 2017). Listen to his Subversity Brexit podcast on iTunes or Spotify