The scene, Cardiff. The date, 16 June 1998. The European summit of heads of state and government has just ended, rounding off the UK’s six-month EU presidency. Tony Blair, who has chaired the summit, is holding a press conference. The EU correspondent for the Daily Telegraph puts up his hand and launches into a tirade that is not so much question as full-blown editorial. Blair, a product of the same public-school system as the questioner, quips: “Boris, you should be prime minister!” Twenty-one years on, this prophecy looks likely to come true.

In Brussels, officials who remember Boris Johnson from his days there (from 1989 to 1994) are dumbfounded. Known to this day as a “buffoon”, he is the source of many painful memories. The son of a former Eurocrat and member of the European parliament, he made a lasting impression as the inventor of the “Euromyth”, a journalistic genre now termed fake news. With the backing of his editors it seems, he eagerly misrepresented events or even completely made up stories to portray the European commission as a bureaucratic monster making absurd proposals. As he once explained to me, aged 28 and dressed as ever in a rumpled jacket, his shirt spilling out in typically English manner: “You mustn’t let facts get in the way of a good story.” Among other yarns, he claimed there were plans to establish a “banana police force” to check the fruit was the right shape, that coffins would be standardised and prawn cocktail crisps would be outlawed. He was quick to highlight the purportedly extravagant lifestyle of overpaid, tax-exempted Eurocrats.

How can you counter someone who has no illusions about a profession he only practises to gain leverage?

For many on the continent, Johnson was then, and remains, the epitome of what is worst in the English (not British) elite: public school, Oxbridge, arrogant, cynical, mildly xenophobic and quite certain of their cultural superiority. On this last point – wholly at odds with the popular image Johnson seeks to promote – he came across as extremely sharp and well-read, and was the envy of many of his European colleagues. A Spanish journalist has a memory of him on a plane reading a book in ancient Greek. In the days when French was the only language authorised in the EU press operation, Johnson once asked a question in Latin. He wanted to know more about some directive supposedly intended to enforce the use of the Latin names of fish to facilitate the common fisheries policy. When Johnson was at a press conference there was never a dull moment.

In human terms, he made no secret of being a dilettante, a comradely guy, who enjoyed life and was always ready to lend a hand. Above all, he was perpetually on the lookout for a good story. In a booming voice he would repeatedly ask me: “What’s the story today, Jean?” You had to pick your words carefully, or run the risk of the Telegraph printing some daft, uncorroborated tale.

Yet he seemed completely guileless, never the hardline ideologue depicting the EU as a remake of the thousand-year Reich and the root of all evil. On the contrary: put simply, here was a man of little principle, amused by everything and not remotely bothered about the consequences of what he wrote or the damage he might be doing. Blessed with a great sense of humour he had no difficulty silencing even the most outspoken critics.

After all, how can you counter someone who owns up to his fibs and has no illusions about a profession he only practises to gain leverage? In this respect he was utterly successful. He managed to bring about a permanent shift in the British media, not just the conservative press, eager to copy his success with his Euromyths, a form of journalism that eventually paved the way for Brexit. I remember a Times correspondent – a paper that sacked Johnson early on in his career for making up a quote – on the verge of tears as he explained that his copy had been completely rehashed in London to match the growing Eurosceptic mood there. Of course the truth about the EU’s activities was always less spectacular, but not so likely to make the front page.

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That this spoilt child of a man – who lies like a toddler and has only the vaguest of political convictions – should be closing in on power gives the UK’s partners overseas the impression that the end is nigh. This, it seems, will be the final act of a political drama launched by Johnson’s fellow old Etonian David Cameron when he chose to organise a referendum on British membership of the EU. The inability to implement the resulting leave vote and actually leave has made the UK an international laughing stock.

Ultimately Johnson is the epitome of the British ruling class, who in their quest for power are happy to gamble cynically with the future of their country and the livelihoods of their fellow citizens. But his lack of any real direction or belief may yet prove an asset, because he is completely unpredictable.

Many in Brussels believe he is capable of any move, even backtracking and shelving Brexit if he thinks it could be turned to his personal advantage. After all, before becoming one of the leading lights in the leave campaign, he was for a long time against the idea of the UK leaving the EU. A pragmatic buffoon, in other words, might be better than a fanatic. Watch out though: Johnson is also capable of taking Britain over the cliff. It would be totally at odds with the statesmanship of his political idol, Winston Churchill, but Boris Johnson might think it amusing.

• Jean Quatremer is Brussels correspondent of Libération