Riotous summers seem to occur in Britain with about the same frequency as sunny ones: roughly every decade. Sometimes it’s Afro-Caribbeans protesting (Brixton in 1981), sometimes Asians (Oldham in 2001). The white working classes rioted over the poll tax in 1990 and in Southport this year. The riot in Harehills, Leeds, last month was precipitated by social services removing children from a Roma couple.