The Yorkshire pudding was invented to catch fat. Its original name, in the first recipe ever printed, was the dripping pudding. That recipe appeared in 1737. A joint of mutton turned on a spit in front of the kitchen fire. As it roasted, the fat ran out of it and fell, hissing, into the hearth. It was the most valuable thing in the meal, and it was going up the chimney. So some northern cook slid a pan of pancake batter underneath. The fat dripped into it for the whole of the roasting. The batter fried from below and soaked from above, and rose into something crisp, hollow and rich. The recipe tells you to shake the pan now and then, so that it is "light and savoury". Ten years later a cookery writer called Hannah Glasse printed it again and gave it the name of the county it came from. It was served first, on its own, with gravy. That was the point. A family filled up on pudding, which was cheap, and the joint went further. The old rule at the table was that those who ate the most pudding got the most meat. So the nation's favourite side dish began as a device for making sure not one drop of animal fat was lost. It still only works properly one way. The tin has to be smoking with beef dripping before the batter goes in. Made with oil it comes out pale and tastes of cardboard. In 2008 the Royal Society of Chemistry solemnly ruled that a true Yorkshire pudding must stand at least four inches tall. Britain kept the pudding, built a standard for it, and threw away the dripping it was designed to save.