In the 1920s, she met Joseph Grossman of Stoll Pictures which led to work as an extra in The Wandering Jew and in the thriller series The Old Man in the Corner.

[citation needed] In 1929, Baker left a typing job at Barcley Corsets in Welwyn Garden City, for the scenario department of British Instructional Pictures.

The couple achieved their greatest joint success with The Seventh Veil (1945) for which they gained the Academy Award for Best Writing, Original Screenplay in the following year.

[6][7] After the war, the Rank Organisation hired her husband to head Gainsborough Pictures, where she was in charge of the scenario department, writing scripts for a number of light comedies, including two for child star Petula Clark, Easy Money and Here Come the Huggetts (both 1948).

She favoured scripts with topical and frequently controversial themes, including Irish politics, teenage sex, abortion, illegitimacy and syphilis — consequently, several of her films were banned by local authorities.

[7] She pursued her favourite subject – the female experience – in a number of films, including Street Corner (1953) about women police officers, Somerset Maugham's The Beachcomber (1954), with Donald Sinden and Glynis Johns as a resourceful missionary, again working with Donald Sinden on Eyewitness (1956) and a series of comedies about the battle of the sexes, including The Passionate Stranger (1957), The Truth About Women (1958) and her final film, Rattle of a Simple Man (1964).

[7] Muriel Box left film-making to write novels and created a successful publishing house, Femina, which proved to be a rewarding outlet for her feminism.