That Boris Johnson managed to get away with a New Year’s beach holiday with his girlfriend Carrie Symonds on the glitzy private island of Mustique tells you quite a bit about the confident state of mind of the prime minister.

Despite Labour leadership candidate and shadow foreign secretary Emily Thornberry referring to the PM as “sunning himself, drinking vodka martinis”, at a time when Donald Trump had given orders to assassinate Iran’s ‘most wanted’ terrorist general, Qasem Soleimani, the overall impression was that Johnson had by good fortune gotten away with it.

That was partly because he had so recently faced the electorate that he was taking his exclusive holiday at a time of maximum political strength. It was also because Mustique is excellent for privacy: not a single photo of Johnson and girlfriend Carrie Symonds on the beach emerged to fix in the public imagination the idea of Johnson as an absentee PM.

Even so, it was a revealing choice. Where prime ministers choose to go on holiday can tell you a lot. For the chillaxing David Cameron to have flown to Mustique to stay in a £20k a week luxury villa – Johnson was reportedly a guest of the Von Bismarck family – within a few weeks of forming the coalition government would have been unthinkable.

Cameron lacked the comfort of an 80-seat majority. During his premiership, we usually got stage-managed PR pictures of the then …