Legend has it that every English schoolboy knows three things about the battle of Waterloo. Each turns on a supposed remark by the Duke of Wellington. The battle was ‘won on the playing fields of Eton’; English footsoldiers were ‘the scum of the earth, enlisted for drink’; and, in a charge near the battle’s end, when his cavalry commander had his right knee puréed by French grapeshot – ‘By G_d, sir, they have shot off my leg’ – the Duke responded with puckered sangfroid: ‘By G_d, sir, so they have.’