She was born Isabel Hodgkinson in Aldridge, Staffordshire, in 1918. Her first ambition was to be an art teacher. She studied painting at the Birmingham Art School and in 1937 joined the Cheltenham Repertory Company as a scenic artist. Soon she was taking both acting lessons and small parts with the company. "It was inevitable, with her ravishing looks," commented one of the company later.
After appearing with repertory companies in Brighton and Norwich, she made her London debut on 1 May 1940 as Maggie Buckley in an adaptation of Agatha Christie's thriller Peril at End House, following this with a Shakespearean role, Mariana in Robert Atkins's Regent's Park production of All's Well That Ends Well. A major break came in 1943 when she played Jenny in John Gielgud's celebrated production of Congreve's Love for Love at the Phoenix.
The following year she was asked to join Gielgud's repertory company at the Haymarket, again playing Prue in Love for Love, but also understudying Peggy Ashcroft as Ophelia to Gielgud's Hamlet (the last time the great actor played the role). She played Ophelia several times when Ashcroft was sick and followed this with a performance as Hermia in A Midsummer Night's Dream which, according to Harold Hobson, was "as pretty and sharply defined as it was lovely".
When Beaumont asked her to go with Gielgud's company to tour India, but only to play the role of the maid in Coward's Blithe Spirit and again to under-study Ophelia, she refused and Beaumont made it clear he considered her ungrateful. She never worked for his management again and made few more West End appearances. Instead she played leading roles in Oxford, Brighton and the Boltons Theatre, including a luminous Juliet.
She returned to the West End in 1956 to play Mary Dallas in the thriller The Night of the Fourth at the Westminster, and three years later played Miss Frost, the Catholic lodger seduced by a young student, in the hit production of J.P. Donleavy's The Ginger Man at the Fortune.
She had meanwhile become a familiar face on television. She had the principal female role in Nigel Kneale's enormously popular blend of science-fiction and horror The Quatermass Experiment (1953), six 30-minute episodes which went out live, with filmed inserts. Dean played the scientist whose astronaut husband returns from a mission with an alien infection that causes him to mutate into a vegetable-like creature.
When A Life of Bliss, a successful radio comedy series, was transferred to television with its original star, George Cole, as the bumbling bachelor hero, Dean was cast as his forthright sister Anne.
Other television roles included Jane Austen's Sense and Sensibility, David Mercer's The Parachute (as mother to John Osborne), Julian Bond's 13-part series A Man of Our Times and a high-toned soap-opera, 199 Park Avenue, sat in a luxury apartment block where the stories of the inhabitants are linked by a gossip columnist searching for stories. Created and written by Dean's husband, William Fairchild, it went out twice weekly, but lasted only nine weeks. (Dean's 1953 marriage to Fairchild, who wrote such screenplays as Morning Departure, The Malta Story and Star!, was dissolved in the early Seventies.)
In the theatre, she had successes in several contemporary plays, including the Royal Court production of John Osborne's A Hotel in Amsterdam (1968), which moved into the West End, and in provincial productions of Orton's What the Butler Saw and John Bowen's chilling Robin Redbreast. She had a particularly notable triumph as Hester in Rattigan's The Deep Blue Sea (at Guildford in 1971 and Nottingham in 1972), once more following in the footsteps of Peggy Ashcroft. Her wrenching portrayal of the clergyman's daughter, married to a High Court judge, who leaves her husband to pursue a hopeless and obsessive affair with a young air force pilot, clearly demonstrated that Dean's gifts had not always been appropriately exploited.
In 1977 she played with Gielgud, for the first time since she had been his Ophelia, in Julian Mitchell's Half Life at the National Theatre.
Dean's film career began in 1943 with a tiny role in The Man in Grey. Later films included Lean's The Passionate Friends (1948), and Sidney Gilliatt's The Story of Gilbert and Sullivan (1953), in which she was the epitome of droll elegance as wife to Robert Morley's Gilbert. "How does it feel to be married to a transcendent genius?" asks her husband as he puts the finishing touches to The Mikado. "I suppose I've always taken it for granted, dear," is her reply.
In Alexander Mackendrick's A High Wind in Jamaica, she presented a beautiful and touching picture of Victorian motherhood in the film's early sequences. Her last appearance on the West End stage was as the tragic mother of Alan Turing (Derek Jacobi) in Hugh Whitemore's Breaking the Code (1986).
A few years earlier the critic Harold Hobson had written: "Our own stage is rich in actresses of whom the chief jewel is Peggy Ashcroft - and the most undervalued is Isabel Dean."
Isabel Hodgkinson (Isabel Dean), actress: born Aldridge, Staffordshire 29 May 1918; married 1953 William Fairchild (two daughters; marriage dissolved); died 27 July 1997.