The shooting dead of a young black man by a white policeman provokes protests and rioting, amid accusations of police racism. In 2011 it happened in London, then spread elsewhere. It has happened this year in Ferguson, Missouri, and protests have spread to other American cities. The latest American outbreak followed a decision not to indict the policeman involved for murder, and the evidence – again similar to the London case – showed him acting spontaneously under stress in a dangerous situation. There are other similarities. Both in Britain and America, black unemployment averages at about twice the national figure. Both in Britain and America, there is a tense national debate about immigration and its effect on the labour market, in particular whether it undercuts the indig