Yet again, America has laid on what is, to British eyes, a horror show. A white policeman goes after a black teenager for jaywalking, and ends up shooting him dead. Protests ensue, attended by his stepfather who carries a sign saying how police "just executed my unarmed son". As protests grow, Molotov cocktails are thrown and riot police called in - this time armed with automatic guns and mini-tanks supplied by the Pentagon. The streets of Ferguson in St Louis start to look like a battle zone - and one that seems to put on display a brutal world of American inequality.