To get a sense of where the UK’s reputation in the rest of Europe is heading, go to the Frankfurter Allgemeine Zeitung (FAZ) website and type in the name of the British foreign minister. Then think of what an ordinary German reader will make of these search results:

“How Boris Johnson makes a fool of himself in an interview.”

“New Zealand: Boris Johnson makes jokes about the Maori indigenous people.”

“Boris Johnson whistles – editorial.”

“Boris Johnson: the EU should pay for Britain’s departure.”

“Boris Johnson, the man who never believes his own sentences.”

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And so on. Arguably the most serious newspaper in Europe (it only introduced colour photographs on the front page in 2007), the FAZ is extremely critical of eurozone policies and of Angela Merkel. It is in favour of strong ties with the anglophone world, and with its economically liberal, free-trade outlook the newspaper should have among its readers many who think of themselves as allies, friends or even admirers of Britain.

But perhaps that last sentence should now be in the past tense. These are increasingly trying times for Britain’s allies and friends in Europe. Imagine you have been a European anglophile all your life, presenting Britain to your friends and family as the country of democracy and the rule of law.

You have defended Britain by pointing out that in the EU referendum both sides resorted to exaggeration and lies. You have told them that this is how politics works these days and that Britain will surely now be returning to its age-old traditions of honesty, pragmatism (keep calm and carry on), competence and reliability.

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Over the past 18 months this must have been a hard enough case to defend, with Theresa May displaying extraordinary ineptitude over the Brexit process, the Daily Mail portraying fellow citizens with a different point of view on the EU as “traitors” and Brexiteers denying parliament the final say over a Brexit process meant to restore parliament’s sovereignty.

Britain’s friends must have been struggling to defend all this, but fortunately their friends and family will have had other things on their minds, following British politics only superficially – it is pretty rare to see a story about Brexit on a European front page. But news of how Britain has become its own worst enemy does get through and with his 4,200-word article in the Daily Telegraph, Johnson will have dealt another blow to Europeans’ admiration, sympathy or even respect for Britain.

Politicians have been lying for as long as they have been around. But with the exception perhaps of Silvio Berlusconi, they always did so surreptitiously, at least pretending to speak the truth. Johnson, however, displays an almost psychopathic pleasure in shamelessly telling lies. What kind of message does that send to our children, to dictators the world over, and to fellow European leaders who find themselves having to cooperate with a man who is simply unreliable? What kind of country would appoint a man such as Boris Johnson to such an important office?

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For more and more Europeans the answer to that question is: a country that no longer deserves our friendship.

How can non-European countries trust Britain to uphold trade agreements if it refuses to keep its promises to the EU?

It is not just the untruths. As an EU member Britain has outstanding obligations and these must be settled. That is not an extortionist “exit fee” or a “Brexit bill”. It is simply a case of the rule of law needing to be observed. Over the centuries British law has built up a formidable reputation, which is why European corporations prefer to settle international disputes in British courts – creating a legal industry that earns the UK a whopping £3.4bn in overseas fees. But how is that reputation for legal reliability to be squared with the promise by Johnson and his fellow Brexiteers to renege on commitments their country has made as an EU member? How can non-European countries trust Britain to uphold new trade agreements if it refuses to keep its promises to the EU?

These are some of the questions in the minds of all those Europeans who once thought of themselves as pro-British. Many of those live in Germany, a country still intensely grateful for the sacrifices Britain made to rid the world of the Nazis. German mainstream politics is extremely polite, leading many commentators to say that the election debate earlier this month between the two main candidates Angela Merkel and Martin Schulz looked more like coalition talks than a clash between opposing views.

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It is highly unusual for German mainstream politicians to say something rude or even forthright and so it should give Britain pause that the recently departed German foreign minister Frank-Walter Steinmeier broke with this custom when asked to describe his British counterpart.

Ungeheuerlich was Steinmeier’s term: monstrous. Around the same time rumours began to spread that Steinmeier had told aides that he simply “cannot stand being in the same room” as Boris Johnson. The amiable Steinmeier never took the trouble to deny the rumour even though he still runs into journalists quite a bit. Because Steinmeier is now the president of Germany.

• Joris Luyendijk is an author