Nancy Spain was born in Jesmond, a suburb of Newcastle-upon-Tyne, England, the younger of two daughters of Lt.-Col. George Spain, an aristocrat, writer, and broadcaster, and his wife Norah Smiles. She attended the Roedean School, a family tradition, and played numerous sports. She played lacrosse for Northumberland and Durham and hockey for the North of England. She became a sports reporter for the Newcastle Journal and acted on BBC Radio. During World War II, she served with the Women's Royal Navy Service, known as the Wrens, as a driver and then as a press officer in London. After the war, she published a memoir, Thank You, Nelson (1945), and then a series of detective novels set at a girls school based on Roedean, beginning with Death Before Wicket (1946). In the 1950s and '60s, she became a star columnist for the Daily Express, She, and the News of the World, and made many radio broadcasts, particularly on Woman's Hour and My Word!. She also appeared on BBC-TV's version of the panel game What's My Line?.
Other books included another volume of memoirs, Why I'm Not a Millionaire (1956), a biography of her great aunt, Mrs. Isabella Beeton, and cookbooks. She had many famous friends, including Noël Coward and Marlene Dietrich. In 1964, she died in a plane crash near Aintree racecourse outside Liverpool at age 46.