Yet his convention-breaking is itself conventional. He is a product of the British class system – Eton and Oxford. He read classics at Balliol. In these circles the British love an eccentric, and Johnson from early in his career was keen to give them one. He became a journalist on conservative-leaning papers – The Times, The Daily Telegraph – before becoming editor of The Spectator, a small magazine with large influence on the right, and during his time at least, characteristics which matched Johnson’s own.

Johnson’s Spectator was eccentric, witty, well-educated and outspoken to the point of rudeness. Later editors struggled to maintain Johnson’s tone of cheerful naughtiness, and the magazine lapsed too often into something more conventional: dyspeptic right-wing anger about absolutely everything.

Having seen it win readers as an editor, Johnson adopted naughtiness in his subsequent political career. As an MP and member of the shadow cabinet, he managed to keep to most of the Conservative platform most of the time, but when he defeated Labour’s "Red Ken" Livingstone to become lord mayor of London, he was let off the leash. He has made a habit of offending prominent individuals, world leaders, sensitive minorities and whole nations with careless abandon – and then apologising profusely. At various times he has insulted Hillary Clinton, Barack Obama, Donald Trump, and Angela Merkel. He won a competition with an insulting limerick about Turkey’s president Recep Tayyip Erdogan. One enterprising newspaper published a BoJo Insult Generator, and invited readers to find out “what Boris Johnson would call you”.

Boris Johnson arrives to see off World War II veterans when he was lord mayor. Credit:Reuters

Apologising is also part of his schtick. After Port Moresby’s high commissioner complained that he had accused the people of Papua New Guinea of cannibalism and chief-killing, he said he meant no insult, and was happy to “add Papua New Guinea to my global itinerary of apology”.