After serving for a mere 45 days, Liz Truss has become the shortest-serving prime minister in British history. George Canning, the previous holder of this record, was forced from office because he died of tuberculosis. Truss, by contrast, is entirely the author of her own demise. But even though her short premiership has no doubt left her own political talents utterly discredited, it would be a mistake to stop apportioning blame there. In fact, Truss’s elevation and downfall show how the British Conservative party has lost touch with reality over the past decade in ways which mirror the descent of the American right.

Truss was forced from office after unveiling a budget that was profoundly out of touch with the realities of modern Britain. A diehard libertarian, she announced steep tax cuts for the rich, including removing an immensely popular cap on bankers’ annual bonuses. Much like the Trump tax cuts of 2017, these moves were supposed to be paid for by generating trickle-down economic growth – and when that failed to happen, as it inevitably does, public service and welfare cuts would follow. This kamikaze libertarianism was combined with sheer nastiness towards the poor, such as when the chair of the Conservative party told voters worried about rising energy bills to either go and get a better-paid job or “freeze”.

So dire were Truss’s plans that even the markets rejected them, causing a financial crisis and ultimately her unceremonious ejection from office. But just getting rid of Truss is not going to solve the Conservative party’s problems. Instead, it must face up to ideological blinders and delusions of grandeur which led it to put Britain in this situation to begin with.

The first entry on the charge sheet is the party’s long-running flirtation with an extreme variant of libertarian economics. Far from being some bizarre outlier, Truss was comfortably elected in a party leadership race this summer despite making no secret of her plans. She was also enthusiastically embraced by rightwing talking heads and thinktanks who have long advocated for precisely the measures in Truss’s budget. Truss was not on a lone ideological bender but was seeking to implement the orthodoxy of a key set of conservative elites – precisely the reason they promoted her into a job she was manifestly unfit for in the first place.

But a much larger issue is the way that Brexit transformed British political discourse, introducing a fetish for anti-intellectualism and bold, ill-thought-through action which is reminiscent of how Trump transformed Republican politics in the United States. The party has become addicted to elevating cranks who promise an impossible return to Britain’s former heyday and to sneering at the policy and economics experts who point out the reasons why this is impossible. For a party that has long cast its critics as unpatriotic and over-educated, it was a small step from the fairytale of Brexit to the fairytale of Truss’s economic program.

Another way in which the party is culpable is its refusal to face up to the contradictions of Brexit, which was always animated by two very different impulses. The first, most important to the average Brexit voter, was to reduce immigration and embrace the culture wars which went along with that goal. The second, embraced mostly by Tory party elites, was to turn Britain into a libertarian economic paradise, which by contrast would require liberal immigration policies to replace the workers shut out by Brexit.

Much like their counterparts in the modern Republican party, Tory elites failed to realize how successful their cynical turn against immigration and towards the culture wars would be. What they originally saw as an electoral strategy to get them into office and allow them to move onto their libertarian agenda eventually became the defining characteristic of their whole movement. In America, this process produced Donald Trump. In the UK, it produced Boris Johnson, who pledged to deport unauthorized immigrants – even those fleeing Ukraine – to Rwanda. Truss seems to have entirely failed to notice this change in conservative politics and tried simply to ignore it, setting up a collision with a large chunk of her own party.

So completely did Truss’s premiership embody the policies and tendencies of a certain set of Conservative party elites that its implosion seems to herald the final destruction of their project. This might seem like something to celebrate, but it will in fact probably lead to the further Trumpification of her party. Facing the direct repudiation of their libertarian program and unable due to their own ideological blinders to consider realigning with the EU, Conservatives are likely to see only one way forward: rushing into the culture wars and trying to smuggle whatever parts of their plutocratic agenda they can along with them.

For America and the rest of the world, this means a Britain that will continue to become more insular, smaller in its ambitions, and weaker in its capabilities. Conservative elites will continue to find many people to blame for this rather than looking in the mirror. But if they really want to repair the damage to their house, they have to begin by looking at the rotting foundations that they themselves laid.

• Andrew Gawthorpe is a historian of the United States and host of the podcast America Explained