Did you know that Maria Ann Smith was genuinely a grandmother who died not knowing that she had given the world one of the best varieties of apple? Or that the word tawdry, meaning tacky or tasteless, has its origins in the fate of a seventh-century Saxon princess, Etheldreda, who was canonised and became St Audrey? Or that when we say Fanny Adams, meaning nothing, this expression is derived from the tragic fate of a real little girl who was murdered in a most horrible fashion? An eponym is a...