People of a certain age insist that today's stars of stage, screen and television can't hold a candle to show-business luminaries of the past. A pronounced element of glamour, not to mention style, has disappeared from the scene. Cher is hardly Garbo. Madonna couldn't stand on the same stage with Merman. And so on. I suspect that 30 or 40 years from now, today's young folk will be saying the same about their current heroes and heroines. We tend to protect and exalt our own icons.

But today's nostalgia brigades have a point. There is no doubt that certain popular figures from movies in the 1930's and 40's had the kind of special presence that is sorely lacking in the contemporary scene. You need go no further than the subject of an hourlong album of photographs and film clips being broadcast tonight at 10 on ABC: ''Cary Grant: A Celebration.'' Michael Caine, the host, doesn't exaggerate when he calls Grant ''the idea, the very ideal, of movie stardom.''

Grant, who died in November 1986, had a movie career that spanned nearly 35 years, most of them at the very top. There are dark and murky patches in his biography. Born and brought up in Bristol, England, he saw his mother placed in a mental institution. He was divorced four times before finding contentment with a fifth wife in his final years. He arrived in New York in 1920 and stayed to work in vaudeville and musical comedy. He didn't get to Hollywood until 11 years later, and then worked in 20 forgettable films before Mae West trained her practiced eye on his possibilities.

In a series of screwball comedies that included ''His Girl Friday'' and ''Bringing Up Baby'' he firmly established his on-screen image of romantic elegance, even while doing somersaults and pratfalls. Someone observes that he became to black-tie what Fred Astaire was to white-tie. Ridiculously handsome, he developed the shrewd trick of always seeming surprised and amused by the effect he had on women. And the women in his screen life were formidable: Katharine Hepburn, Rosalind Russell, Marlene Dietrich, Ingrid Bergman, Deborah Kerr, Grace Kelly, Marilyn Monroe, Sophia Loren and Audrey Hepburn. Talk about your good old days.

This television tribute - produced and directed by Mel Stuart and written by Richard Schickel from his book about Grant - is filled to bursting with scenes from Grant's films, from the earlier comedies to the extraordinary series with Alfred Hitchcock (''Suspicion,'' ''Notorious,'' ''To Catch a Thief,'' ''North by Northwest'') to some of the more popular but minor successes later on. His biggest box-office success was ''Operation Petticoat.'' After ''Walk, Don't Run'' in 1966, he retired. He never received an Academy Award for one of his performances. He was awarded an honorary Oscar in 1970 and a Kennedy Center Honor in 1981.

George Cukor, the director, once shared this insight: ''Cary Crant was a handsome man who never acted as if he were.'' Whatever, he was dashing, charming and wonderfully talented. He was also, in a perhaps unsettling way, a complete creature of the movies. He once said: ''I pretended to be someone I wanted to be, and finally I became that person.'' The element of magic in his career is undeniable.

The executive producers of ''Cary Crant: A Celebration'' are, in keeping with past echoes, Jack Haley Jr. and David Niven Jr.