Her elder brother was the actor, author and playwright Geoffrey Kemble Grinham Keen (1895–1971), who used the stage name Geoffrey Kerr, and her older sister was Lucy Joyce Gunning Keen (1897–1980), who acted under the stage name Joyce Kerr before marrying, in 1924, James Boswell Talbot, 3rd Baron Talbot de Malahide (1874–1948).
[5] Kerr made her stage debut aged 17 in 1921 in Threads by Frank Stayton playing Chloe, the daughter of a judge.
[6] She gained wider notice in her next role, as society girl Diana Oughterson, in The Faithful Heart by Monckton Hoffe, which opened at the Comedy Theatre in November 1921 and ran for 185 performances.
[6] In September 1925 The Vortex transferred to the US and played for 157 performances, mostly at Henry Miller’s Theater in New York, where Coward, Lilian Braithwaite and Kerr repeated their roles until it closed in January 1926.
[6] In April 1929 she produced and directed the only play that she wrote, Requital, which had 15 performances at the Everyman Theatre in Hampstead, starring Peggy Ashcroft.