Author of Quidditch Through the Ages, The Wonder of Wigtown Wanderers, He Flew Like a Madman, and Beating the Bludgers. He lives in Nottinghamshire. His hobbies are backgammon, vegetarian cookery, and collecting vintage broomsticks (QA).
"Wisp" = Old English for a small bundle of straw (such as the end of a broom).
Perhaps related to "will-o'-the-wisp", (where wisp relates to the tendril of smoke from a candle which floats away on the air), and therefore "something which deludes or misleads."