'Butcher' Cumberland is portrayed as one of the arch villains of British history. His leading role in the bloody defeat of the Jacobite rebellion in 1745 and his ruthless pursuit of Bonnie Prince Charlie's fugitive supporters across the Scottish Highlands has generated a reputation for severity that has endured to the present day. He has even been proposed as the most evil Briton of the eighteenth century. But was Prince William Augustus, Duke of...