Early life and career thumb|left| Cooper was born at 23 Ennersdale Road, Hither Green, Lewisham, London, the eldest of the three daughters of Charles William Frederick Cooper (1844–1939) and Mabel (Barnett) Cooper (1861–1944). Her two younger sisters were Doris Mabel (1891–1987) and Grace Muriel (1893–1982). Writer Henry St. John Cooper was a half-brother. Cooper spent most of her childhood in Chiswick, where her family moved when she was an infant.
Early life and career thumb|left| Cooper was born at 23 Ennersdale Road, Hither Green, Lewisham, London, the eldest of the three daughters of Charles William Frederick Cooper (1844–1939) and Mabel (Barnett) Cooper (1861–1944). Her two younger sisters were Doris Mabel (1891–1987) and Grace Muriel (1893–1982). Writer Henry St. John Cooper was a half-brother. Cooper spent most of her childhood in Chiswick, where her family moved when she was an infant.