The actress, Louie Ramsay, has died. Her father Dr Melvin Ramsay helped found the ME Association.

Obituary in The Guardian, 16 March 2011 (words by Michael Coveney).

Louie Ramsay, who has died aged 81, was a dynamic musical comedy actor who became a dramatic linchpin of Laurence Olivier's National Theatre Company at the Old Vic and then found wider fame as Dora Wexford, the wife of Inspector Wexford, in The Ruth Rendell Mysteries, starring George Baker, who became Louie's second husband.

She was noted for her warmth, elegance and sense of humour, describing herself as a small woman with a big voice – the loudest in the chorus, said Mary Martin, whom she understudied as Nellie Forbush in the West End premiere of South Pacific. She also convinced Rendell that she should make her role in Wexford less passive: in one of the 23 episodes, screened between 1987 and 2000, Dora became the target of environmental terrorists and was taken hostage.

Louie was born in Molteno, in the Eastern Cape, South Africa, where her Scottish father, Melvin Ramsay, had taken up a medical post. On returning to Britain, he became a consultant physician at the Royal Free Hospital in Hampstead, north London, specialising in infectious diseases and founding the ME society after conducting the principal research into the disease.

She was educated at the North London Collegiate school and Rada, where she formed lifelong friendships with Sean Connery (who later joined her in the South Pacific chorus) and Patricia Hitchcock, Alfred Hitchcock's daughter. She made her film debut in a tiny role in Hitchcock's Stage Fright in 1949.

She arrived in the West End in 1950 in a revival of Harold Brighouse's Hobson's Choice, starring Wilfred Pickles and Eunice Gayson. After South Pacific in 1951, she joined the Players' Theatre, where in 1955 she stopped the show nightly in Twenty Minutes South, a musical comedy by Maurice Browning and Peter Greenwell, about the love affairs of a group of office workers, directed by Hattie Jacques and starring John Le Mesurier; this led to a leading role in 1956 opposite Max Bygraves in Meet Me on the Corner.

In the same year, she married the Irish Canadian actor Ronan O'Casey, but only a few weeks later was paralysed by Reiter's syndrome and told she might never walk again. She recuperated in Majorca and sang there in a local restaurant to regain her confidence, returning to London to star opposite Bernard Cribbins in Harmony Close by Charles Ross and Ronald Cass at the Lyric, Hammersmith. As both a stage star and a medical example, she was the subject of Eamonn Andrews's television show This Is Your Life in 1958, broadcast live from the King's Theatre in Edinburgh, where she was appearing opposite Jimmie Logan in pantomime. Connery arrived before the show to give her a “spontaneous” tour of his old milk round, acting as a decoy for the BBC production team.

During the 1960s, she presented the children's television show Ollie and Fred's Five O'Clock Club, and made a guest appearance as a creepy nanny in the long-running Avengers series. She joined the National Theatre in 1971, appearing with Maureen Lipman and Sarah Atkinson as one of three Randy Ladies invited home by the poet William Blake in Adrian Mitchell's Tyger.

In the next few years at the Old Vic, she appeared in John Dexter's productions of Peter Shaffer's Equus and Tony Harrison's brilliant translation of Molière's The Misanthrope, with Alec McCowen and Diana Rigg, and as Joan Plowright's sister in Olivier's acclaimed production of JB Priestley's Eden End. On the first night, taking a curtain call with Olivier and Priestley himself, she said to herself quietly: “Lou, I think you've just peaked.” Olivier also cast her as Miss Adelaide in the Guys and Dolls that never happened.

She played matriarchal leads in two BBC series of the 1980s, King's Royal and Strike It Rich, before going into Inspector Wexford. She had divorced O'Casey in 1979 and married Baker in 1993. She spent her last years with Baker near Devizes in Wiltshire, where she was an enthusiastic gardener and walked her dog over Salisbury Plain. Both husbands survive her, along with her son Matt O'Casey, a film-maker, three grandchildren and five step-daughters.

* Kathleen Louie Ramsay, actor, born 25 November 1929; died 6 March 2011