Clemence Dane was born Winifred Ashton in Kent, England. After completing her education at age 16, she was hired to work as a French tutor in Switzerland. A year later she left, and studied art in England and Germany. Although she showed promise as a painter, she gave up her career as an artist to become an actress and then a teacher. She began writing while recuperating from the stresses of war work in World War I and took the pseudonym "Clemence Dane" from the famous church of St. Clement Danes in London.
Her first published novel, the semi-autobiographical Regiment of Women (1917), was a big success. In 1919, she wrote another successful novel, Legend, which she turned into a play called A Bill of Divorcement. The play was a smash hit in London and on Broadway in New York, and was adapted into a film starring Katharine Hepburn and John Barrymore in 1932. Dane began writing screenplays as well as novels. She co-wrote the screenplay for Anna Karenina starring Greta Garbo. In 1946, she won an Academy Award with Anthony Pelissier for their screenplay for the film Vacation from Marriage, released in the UK as Perfect Strangers.
With Helen de Guerry Simpson, she wrote three detective novels, the first of which, Enter Sir John (1928), was filmed as Murder! by Alfred Hitchcock. She also wrote a nonfiction book on the history of Covent Garden, the district in which she lived for a number of years, London Has a Garden (1964).
In the course of her career, Clemence Dane wrote more than 30 plays and 16 novels.