In 1942 the acting coach at Warner Bros suggested to the 17-year-old stepdaughter of studio head Jack Warner that she might like to read for a supporting role in a forthcoming film. Joy Page thought the script “corny and old-fashioned” and agreed to try out for the movie only because Ingrid Bergman might be in it. The film was called Casablanca.

Warner was not enthusiastic about her participation, but in the event she was perfectly cast as the ingénue refugee and newlywed who seeks Humphrey Bogart’s advice as to whether she should surrender her virtue to the corrupt Captain Renault (Claude Rains) in return for an exit visa. “You want my advice,” growls Bogart. “Go back to Bulgaria.”

He then allows the girl’s husband to win the price of the visa at roulette, a gesture to love that marks the start of his ascent from the cynical despair into which he has drifted. “I’ll forgive you this time,” says Renault, “but I’ll be in tomorrow with a breathtaking blonde. And it’ll make me very happy if she loses.”

The dark-haired Page had led a rather sheltered life until then, shielded from the tensions caused by Warner’s decision to divorce his wife to marry Joy’s mother, and her guileless performance in the film reflected her own simple and well-intentioned nature. It was to prove the only memorable role of her career, but one of which to be proud.

She was born Joy Cerrette Paige (she modified her surname for the film) in Los Angeles in 1924. Her father, Joseph Paige, was a silent screen actor known (under the name Don Alvarado) for Valentino-style romantic leads. His career, however, was to be finished by the advent of the talkies, notably Warner’s The Jazz Singer (1927).

Joy’s mother was the actress Ann Boyar. Her parents divorced when Joy was about 5 years old. After a relationship of some years, her mother then married Warner — who had given Alvarado his stage name — and Joy went to live at his 12-acre estate in Beverly Hills (now owned by another media mogul, David Geffen).

Despite the success of Casablanca, her stepfather refused to put Page under contract for fear of accusations of nepotism, and she made her next film for MGM. Kismet (1944) was a tale of Old Baghdad in which Marlene Dietrich played the Vizier’s wife and Page the daughter of a beggar played by Ronald Colman.

Yet despite such a start to her career, for much of her life she seemed to be not entirely the mistress of her own fate. She was still unsure if film was for her when Warner encouraged her to go out on a date with one of the studio’s young actors, William Orr. Soon Warner had told the papers that the two would marry, and in 1945 they did. Orr became first an assistant producer at Warners, and then from the Fifties onwards the force behind its highly successful television department, which made hit shows such as Maverick, 77 Sunset Strip and Cheyenne.

For a while Page continued to appear in minor roles in lesser films, including Bullfighter and the Lady (1951), with Robert Stack, and as José Ferrer’s love interest in The Shrike (1955). She then moved to television, starring opposite Leslie Nielsen in The Swamp Fox (1959), a Disney serial about the American War of Independence. Later there were guest spots on programmes such as Wagon Train.

By the early Sixties, however, she had retired from acting and, indeed, from life outside her home. Always emotionally fragile, she had found the strains and expectations of the Hollywood system too much for her, and for some 35 years largely withdrew from day-to-day activities. Yet she remained her kind if rather earnest self, and though she and Orr were to divorce in 1970, when he was suffering from Parkinson’s disease before his death in 2002, he came back to live with her, and she cared for him.

She is survived by their son and daughter. Another son predeceased her.

Joy Page, actress, was born on November 22, 1924. She died on April 18, 2008, aged 83