Forbes was born John Theobald Clarke on 22 July 1926 in Stratford, London. From an early age he had set his heart on an acting career and he entered the Royal Academy of Dramatic Arts when he was seventeen, but didn't complete his studies. During the war he served in the Intelligence Corps and later the Combined Forces Entertainment Unit. Changing his professional name to Bryan Forbes, he made his screen-acting debut in 1948 and over the next decade became a familiar and dependable supporting player in a number of notable British films, including The Small Back Room (d. Michael Powell, 1949), An Inspector Calls (d. Guy Hamilton, 1954) and The Colditz Story (d. Hamilton, 1955).

However, acting began to take second place to screenwriting and then directing. He made significant contributions to the scripts of exciting war dramas such as Cockleshell Heroes (d. José Ferrer, 1955) and I Was Monty's Double (d. John Guillermin, 1958), before receiving great acclaim for his screenplay for Basil Dearden's The League of Gentlemen (1959), in which a group of ex-servicemen on the social scrap heap revive their former skills to plan a daring robbery. The film's cynical tone was memorably encapsulated by Forbes in an exchange between Nigel Patrick and Jack Hawkins where the former notices a prominent oil painting of the latter's wife and gently enquires if she is now dead. "No," replies Hawkins, suavely, "I'm sorry to say the bitch is still going strong."

A similar astringency enlivens his script for Sidney Gilliat's frisky version of a Kingsley Amis novel about thwarted adultery, Only Two Can Play (1962). "Still peddling trash to the masses?" asks Richard Attenborough's contemptuous Welsh bard of Peter Sellers' librarian, to which Sellers responds sweetly, "Yes: how about you? Still writing it?" A mention must also be given to his script for Station Six Sahara (d. Seth Holt, 1962), a scorching drama about men in the desert on heat over a woman.

Undoubtedly his most controversial screenplay - and arguably his best - was for Guy Green's The Angry Silence (1960), in which Richard Attenborough is "sent to Coventry" by his workmates after refusing to join an unofficial strike. Left-wing critics were outraged by the film's portrayal of the unions and its caricatured communists, but Forbes (who politically has always leaned to the right) maintained that he achieved a fair balance by portraying the management as equally crass.

His directing career began in 1961 with Whistle Down the Wind, a tender portrayal of innocence in which three Yorkshire children believe the criminal they are hiding in their barn is a reincarnation of Christ. Tenderness was also the hallmark of his next film, The L-Shaped Room (1962), in which a pregnant, unmarried Frenchwoman shares a house with a motley assortment of characters including a writer with whom she falls in love. Leslie Caron was nominated for an Oscar for her leading performance, as were two other actresses for their performances in a Forbes film later in the decade: Kim Stanley as the psychic in Séance on a Wet Afternoon who (1964) instigates a bizarre kidnapping plot in order to draw attention to her powers; and Edith Evans in The Whisperers, a poignant study of loneliness and old age in which Evans gave her finest screen performance. (Forbes was later to be her official biographer.)

Other films during the 1960s, such as the black comedy, The Wrong Box (1966) and a ponderous but intriguingly pretentious thriller, Deadfall (1968), where a robbery is elaborately crosscut with a performance of a John Barry guitar concerto, were less successful but not without interest. By the end of the decade he had established himself as an important figure in the national industry. "I may not have come up the hard way," he would say, "but I have come up the whole way."

In 1969 he was appointed Chief of Production and Managing Director of Associated British (EMI). It was the greatest challenge of his career and was to prove his biggest disappointment. Most of the projects dear to his heart foundered through lack of managerial support and finance; some films that were made were frankly disappointing and, frustrated and thwarted, Forbes resigned in 1971.The venture is now remembered essentially for having produced two charming films for children, The Railway Children (d. Lionel Jeffries, 1970) and The Tales of Beatrix Potter (d. Reginald Mills, 1971), which became respectable money-makers; and for facilitating one masterpiece, Joseph Losey's The Go-Between (1970), which was to win the Golden Palm at Cannes in 1971 and prove a substantial critical and commercial success.

Nevertheless, from that point onwards, Forbes' film career never recovered the impetus of the 1960s. He had made a successful film in Hollywood in 1965, King Rat, a sharp study of opportunism and survival in a prisoner-of-war camp, and ten years later he returned to America and did a similarly capable and well-received job with the thriller, The Stepford Wives (1975), an ironic take on the new feminism based on the novel by Ira Levin. But after the EMI debacle, the British films have been sporadic and lightweight.

Instead, Forbes has written several novels and two highly entertaining volumes of autobiography. Since 1954, he has been married to Nanette Newman, who has appeared with distinction in a number of his films, most notably with Malcolm McDowell as a pair of paraplegics in love in The Raging Moon (1970). He was always good with actors, had an eye for the unusual aspects of love, could write an argument scene as well as the best of them and was a prodigious craftsman with words (it is typical of his literary finesse that the kidnappers in Séance even quibble about the exact wording and punctuation of a ransom note). If there is an element of disappointment about his career, it is simply that a distinctive voice, with a personal and political edge, has not been heard as loudly and as often as one would ideally have liked.