“For us, the UK has always been seen as like-minded: economically progressive, politically stable, respect for the rule of law – a beacon of western liberal democracy,” said Rem Korteweg of the Clingendael Institute thinktank in the Netherlands.

“I’m afraid that’s been seriously hit by the past four years. The Dutch have seen a country in a deep identity crisis; it’s been like watching a close friend go through a really, really difficult time. Brexit is an exercise in emotion not rationality; in choosing your own facts. And it’s not clear how it will end.”

Britain’s long-polished pragmatic image has been “seriously tarnished”, agreed Nicolai von Ondarza of the German Institute for International and Security Affairs. But trust in the UK, too, has taken a very heavy hit on the Brexit rollercoaster.

“That’s particularly been the case over the past year,” Von Ondarza said. “Boris Johnson has always been seen as a bit of a gambler, displaying a certain … flexibility with the truth. But observing him him as prime minister has only made that worse.”

Germans tend to view international politics “very much through the prism of international law”, Von Ondarza said, so the prime minister’s willingness to ignore it – in the form, particularly, of the internal market bill – was deeply shocking.

“The idea that you’d willingly violate an international treaty that you’d negotiated and signed barely eight months previously … That’s just not something you do among allies,” he said. “That whole episode really damaged Britain’s credibility.”

Others were more brutal still. “There is absolutely nothing good about Brexit,” said Nikolaus Blome in der Der Spiegel, which, let’s be honest, “would never have happened had Conservative politicians not, to a quite unprecedented degree”, deceived and lied to their people”.

Much of the British media, Blome said, “were complicit, constantly trampling on fairness and facts”, leaving Britain “captured by gambling liars, frivolous clowns and their paid cheerleaders. They have destroyed my Europe, to which the UK belonged as much as France or Germany.”

But the British prime minister’s lies were the biggest of all, he said: “‘Take back control,’ Johnson lied to his citizens. But all the British government will finally have achieved is to have taken back control of a little shovel and a little sand castle.”

Because the “sovereignty” in whose name Brexit was done remains, essentially, a myth, said Jean-Dominique Giuliani of the Robert Schuman Foundation in France. “It is history, geography, culture, language and traditions that make up the identity of a people,” Giuliani said, “not their political organisation”.

It is “wrong to believe peoples and states can permanently free themselves from each other, or take decisions without considering the consequences for their citizens and partners. ‘Take back control’ is a nationalist, populist slogan that ignores the reality of an interdependent world … Our maritime neighbour will be much weakened.”

The German historian Helene von Bismarck doubted Brexit would bring an end to what she described as a very British brand of populism. “British populism is a political method, not an ideology, and it does not become redundant with Brexit,” she said.

Von Bismarck identified two key elements in this method: an emotionalisation and over-simplification of highly complex issues such as Brexit, the Covid pandemic or migration, and a reliance on bogeymen or enemies at home and abroad.

“Populists depend on enemies, real or imagined, to legitimise their actions and deflect from their own shortcomings,” she said. If the EU has been the “enemy abroad” since 2016, it will steadily be replaced by “enemies within”: MPs, civil servants, judges, lawyers, experts, the BBC.

“Individuals and institutions who dare to limit the power of the executive, even if it is just by asking questions, are at constant risk of being denounced as ‘activists’” by the Johnson government, Von Bismarck said. “Everyone has political motives – except for the government, which seeks to define ‘neutrality’.”

Brexit itself is being framed as “the grand departure, the moment the UK is finally free and sovereign, when all problems can be solved with common sense and optimism – justifying a more ‘pragmatic’ approach to rules, constitutional conventions and institutions” that actually amounts to a “worrying disregard for the rule of law”.

There is no reason to suppose, Von Bismarck said, that the electoral attractiveness of “British populism” would decline once the Brexit transition period ends, especially not when the real, hard consequences of the pandemic and Brexit start to bite.

“It is naive to expect a political style which ridicules complexity, presents people with bogeymen to despise, and prides itself on ‘doing what it necessary’ even if ‘elites’ and institutions get in the way to lose its appeal in times of hardship,” she said.

The past four years, said Elvire Fabry of France’s Institut Jacques Delors, had shown both Europeans and Britons “just how little we really knew each other”. They had also revealed, she said, the fragility of a parliamentary system seen by many on the continent as a point of reference.

“It’s been difficult for us to anticipate, at times even to interpret, what’s happened” in the UK, Fabry said. “The direction Johnson has taken the Conservative party in – we didn’t see that coming. The course he’s setting for the country. The polarisation. And the way MPs have been bypassed since he became prime minister …”

Most striking of all, she said, was how the politics prevailing in Britain had become “detached from geopolitical reality – from the way the world is developing. It’s a political vision turned towards yesterday’s world. Ideological. The way the trade deal focused on goods at the expense of services … It’s not the way the world’s going.”

Painful as the Brexit process may have been for Europeans, however, it has at least demonstrated “the reality and value of the single market, its rules and norms, and of the EU’s basis in law,” Fabry said. “Those are at the heart of the European identity – and defending them has given the union a new political maturity.”

It has also, concluded Korteweg, served as a warning. “I think it’s taught us all just how vulnerable our political processes are,” he said. “Just eight years ago, leaving the EU was a seriously fringe proposition in British politics, and now look where you are. So we’ve seen how fragile it all is, what we’ve built – and how worth defending.”