[7][8] Mitchell trained for an acting career at the London Theatre Studio,[9] making her professional debut in 1939.

[5] Already an experienced stage actress, she made her speaking film debut in The Queen of Spades (1949), although she played an uncredited minor role in Love on the Dole eight years earlier.

[12] Mitchell was voted 'Television Actress of the Year' for 1953 by the Daily Mail newspaper, mainly for her role as Cathy in the Nigel Kneale/Rudolph Cartier adaptation of Emily Brontë's novel Wuthering Heights.

[17] Outside acting, Mitchell was also an established author, writing several books for children and adults as well as winning awards for playwriting.

[5] Mitchell was married to the journalist, film and theatre critic and novelist Derek Monsey (1921–1979) and they lived in a village in the south of France.