I'll explain the science to you later. Meanwhile, I look out the window and there are my dear neighbours, Ken and Catherine and their daughters Kitty and Lucille, on the links beavering feverishly away. First they build a snowman as requested but this is clearly not enough for Ken who, like a hyperactive Inuit, begins to build an igloo, using a shovel and plastic recycling containers to gather and pack the snow. Or rather, Catherine does. Up it goes in no time and is eventually taller than Ken, which is tall enough. From a distance it looks like an ermine cloak worn by a king or, says the Home Secretary, the kind of thing that would scare you witless if you came across it half-cut in the dark.