[2] She made her stage debut in 1927, then worked for several years throughout the United Kingdom, achieving success playing comedic, often eccentric characters in the West End of London.

[4] In 1961 Hickson played the housekeeper in the film Murder, She Said, based on Agatha Christie's novel 4.50 From Paddington and starring Margaret Rutherford as Miss Marple.

Her stage career included roles in Noël Coward's Blithe Spirit, the musical The Card (1975), adapted by Tony Hatch and Jackie Trent from the novel by Arnold Bennett; and Alan Ayckbourn's Bedroom Farce, for which she won a 1979 Tony Award for Best Featured Actress in a Play and had been nominated for the Laurence Olivier Award for Best Comedy Performance in 1977.

Hickson played the role of Miss Marple in all 12 adaptations, which were produced from 1984 to 1992; she received two BAFTA nominations for Best TV Actress, in 1987 and 1988.

When the OBE was bestowed on Hickson in June 1987[5] Queen Elizabeth II was reported to have said, "You play the part just as one envisages it.

[7] From 1958, Hickson lived at 2 Rose Lane, Wivenhoe, along the River Colne 43 miles (69 kilometres) from London in Essex, until her death in 1998.