Ever since 2016, a political echo has travelled to and fro across the Atlantic. Leave’s referendum triumph reverberated in Donald Trump’s shock election win later that year. Last week’s victory for Boris Johnson took cues from the US, with the Conservative demolition of Labour’s ‘red wall’ of Northern and Midlands seats paralleling Trump breaching the ‘blue wall’ of Midwestern states three years earlier.

Now the echo is travelling westwards again, with American politicians, pundits and pollsters looking to the UK for clues as to how next year’s presidential election will play out.

For moderate Democrats, the UK result is a welcome parable. Joe Biden wasted no time in packaging Labour’s collapse as a warning, telling donors at a fundraiser on election night: “Look what happens when the Labour Party moves so, so far to the left. It comes up with ideas that are not able to be contained within a rational basis quickly.”

Indeed, Corbyn’s failure will undoubtedly become a meme in the primary, a proxy for the Democratic party’s internal battle boosted by his endorsement by high-profile American left-wingers like Alexandria Ocasio-Cortez.

What about on the right? Countless comparisons have been made between Johnson and Trump in recent years. They are usually shallow and rarely enlightening, but this time feels different. The parallels are so striking, with Britain’s electoral map redrawn along more American lines, that it is impossible not to wonder what the 2019 Conservative victory means for Republicans in 2020.

There is added interest thanks to Johnson’s fame in his country of birth — a fame few foreign politicians achieve in what can be a fairly self-obsessed political scene. Among the conservatives that populate Washington’s right-leaning think tanks, or fill the offices of Republican senators, that celebrity manifests itself as a caricatured cheerleader for Anglo-Saxon liberty. In these circles, “Boris” is rarely a word said without a smile. A cheeky chappy, a classicist, a biographer of Americans’ favourite Brit, Winston Churchill, and the man who made Brexit happen. What’s not to like?

“I’ve always seen the UK as a leading, not lagging, indicator for American politics,” says the Republican pollster Frank Luntz. “Thatcher’s win in ’79 was a harbinger for Reagan, Brexit told Republicans that there was a hidden vote out there that didn’t talk to pollsters, that was disconnected from the process but would still participate if triggered.”

“In Trumpland, they see this result as a clear indication that the grassroots populist frustration that lead to Brexit and Trump’s election is alive and well,” he says. But is such reflexive confidence justified?

In less Trumpian parts of the American right, the mood is more wistful than triumphant

“Americans tend to read everything through America,” says Republican strategist Luke Thompson. “Everything is part of a heliocentric solar system, with Donald Trump as the sun. On the right there’s a tendency to over-read this as proof positive that Trump will get re-elected, and may even win the popular vote.”

In less Trumpian parts of the American right, the mood is more wistful than triumphant. Conservatives exasperated at the excesses and indecencies of Trump see in Johnson’s emphatic win the possibilities that might be open to them were they not stuck with a candidate that is such a turn off to so many.

As Patrick Ruffinni of Echelon Insights, another Republican strategist, puts it, the UK result demonstrates what you can achieve “if you have someone who is slightly more unifying, with fewer personal grudges and vendettas. That is what separates this kind of unambiguous victory from the muddled one we had in 2016, winning the electoral college but losing the popular vote.”

If Boris’s win is a repudiation of anything, it is of the idea that 2016 was an aberration — a Russia-induced minor setback on the road to ever greater liberalism. In narrow electoral terms, it undermines the naive idea that after Trump, the Republicans can return to a tried-and-tested style of centre-right leadership.

However, the result also drives a wedge between Trump and Trumpism. Britain is such an interesting case study for the American right not because of the similarities between the President and his British counterpart, but because of the differences. Trump’s potency ultimately comes down to his ability to succeed where other Republicans have failed. There now exists a powerful counter-example: a conservative candidate successfully tapped into the same thing as Trump but without having to be quite so, well, Trumpy.

That is as true in government as it is on the campaign trail. In the long run, the more significant thing for American observers of British politics won’t be how Johnson won his majority, but what he does with it. Johnson has the kind of free rein rarely afforded to US Presidents and his team is staffed with competent political professionals, not sons-in-law and lackeys. For those interested in conservative solutions to the problems that have animated politics on both sides of the Atlantic in recent years, that makes Britain an important test bed.

So far, Trumpism has been a diagnosis rather than a prescription: an electorally compelling, though often misleading, account of the way in which America has lost its way. Viewed from Washington, the UK is now a laboratory in which to research a cure. In other words, the Johnson government is a chance to find responsible answers to the combustable questions posed by Trump.

Tempering this transatlantic observation are important differences between Britain and America. As David French at The Dispatch points out, one of those differences is race. It’s easy to forget just how white Britain is compared to the US. “It’s almost Iowa levels of white,” writes French. The risk, as he sees it, from Americans drawing too many lessons from the UK is that, “setting aside the overarching historical and moral issues of national unity, equal opportunity, and equal justice, racial differences create a simple math problem for right-wing populism. There aren’t enough white working-class voters to create a sustainable right-wing populist party — especially since (so far, at least) right-wing populism is unattractive to most educated voters, including voters.”

He’s right, though he is really identifying a problem with Trump — who is capable of jaw-dropping racial divisiveness. An American version of Johnson’s embryonic brand of one nation conservatism would be uniquely American, and it would need an answer to America’s unique set of racial issues.

Like many on the American right, French is busy fighting a civil war: orthodox right-wingers versus the MAGA crowd. Johnson’s win is above all a reminder to American conservatives that there is more to that fight than Donald Trump. If they listen for the echo of the British result in their own politics, those set against the President may like what they hear.