Britain used to be resolutely contemptuous of extreme parties. While Italy lurched from crisis to crisis or the French succumbed to populism, we prided ourselves on moderation. The Communist Party of Great Britain won very few parliamentary seats; the British Union of Fascists and British National Party never won any. Our election nights offer a regular roster of beloved eccentrics: Count Binface wants to nationalise model railways; the Monster Raving Loony Party opposes any takeover of Iceland (the supermarket). But there is nothing remotely humorous about the new populism seen this week in Gorton and Denton.