Could Boris do a Harold Wilson? Over the years there has been much speculation about the sudden resignation of Wilson as prime minister less than a year after he had settled, apparently for good, the momentous question of Britain’s future in Europe via the 1975 referendum. Was he forced out by MI5? Had he already got wind of his early-onset Alzheimer’s? Was there some other hidden personal scandal that would have emerged had he not stood down?

The truth was rather more bland: it seems more likely that Wilson had just lost his appetite for the grind of the job.