Researchers have uncovered a cluster of characteristics called “the dark triad”: psychopathy (cold, callous ruthlessness); Machiavellianism (manipulative game-playing); and narcissism (me-me-me grandiosity). In tests, people who score highly on one of these traits also do so on the other two.

The triad is more common among senior managers and celebrities than in the general population. A study of 200 American senior managers, for example, found psychopathy was six times more common in them, while a British study revealed significantly more narcissism in senior managers than in mentally ill inmates of a prison hospital for violent offenders. The menagerie of charmers and deceivers who were paraded before Lord Justice Leveson in his inquiry into phone-hacking by the British press also illustrated that the triad is endemic in our ruling elite.

The amount of triadic behaviour has generally increased in developed nations, particularly since the 1980s. Narcissism among Americans has ballooned since the 1960s, their egos inflated by the shift from collectivism to individualism. That change was accelerated in Britain by “greed is good” Thatcherism.