A century on, the trail of destruction left by colonialism remains evident everywhere. Brexit is an illusory attempt to restore the UK’s past imperial glories, built on the plunder of colonies. Russian government policy is that it’s OK to invade your neighbours. France’s elections have shrunk to a choice between the centrist candidate of the day and a party founded by a nostalgic veteran of the Algerian war. Many African and South American former colonies suffer from widespread expectations that those in power will rule through varying degrees of violence and graft. The poisonous heritage from Ireland’s colonial past, meanwhile,…