Kay Walsh graced the British Cinema of the 1930s and 1940s as a leading lady, before maturing into character roles. She was born Kathleen Walsh in London, England of Irish parentage. She and her sister Peggy were raised in Pimlico by their grandmother. She began her career as a dancer in the chorus of several Andre Charlot revues, before performing solo in New York and Berlin.
Kay made her screen debut in Get Your Man (1934) and later appeared in The Luck of the Irish (1936). After appearing as a dancer in the West End show "The Melody that Got Lost", the producer Basil Dean signed her to a contract with Ealing Studios. She starred opposite George Formby in the comedies Keep Fit (1937) and Comme sur des roulettes (1938). She met an aspiring film editor David Lean in 1936 and they were married in 1940. She collaborated on several of his films by writing additional dialogue and advising on production and casting.
She made an impression in Ceux qui servent en mer (1942), as Queenie Gibbons in Heureux mortels (1944), as Nancy in Oliver Twist (1948), Vice Versa (1948), Le grand alibi (1950), L'aimant (1950), Vacances sur ordonnance (1950), Encore (1951), La reine vierge (1953), Lease of Life (1954), Les fanfares de la gloire (1960) and Scrooge (1970). She won a BAFTA nomination and a National Board of Review award for Best Actress for "The Horse's Mouth" (1958). She retired from acting after appearing in La nuit de l'évasion (1982).
She was twice married. Following her divorce from David Lean in 1949, she married the Canadian psychologist Elliott Jaques (1917-2003). They adopted a daughter Gemma in 1956, but the marriage was later dissolved. Kay Walsh died at age 93 on April 16, 2005 at the Chelsea and Westminister Hospital from multiple burns, a week after being injured in a fire at her London flat.