Mr. Morley worked tirelessly during much of his varied career, reviewing every show in sight, churning out celebrity biographies at a rapid rate, hosting radio programs, penning the occasional play or revue, and frequently flying back and forth between London and New York.

Within the fairly colorless crowd that is the London critical corp, Mr. Morley stood out as an almost Falstaffian figure. Stout, with a full beard and his father's florid face, he was frequently seen in large, flowing silk shirts of a vibrant shade. He could be counted on to expound at length and with great enthusiasm on any subject in the arts. His colleagues remembered him for his insatiable curiosity and wide knowledge.

As an author, he seemed to be interested in almost everyone. He wrote biographies about John Gielgud, Gene Kelly, Gertrude Lawrence, David Niven, Elizabeth Taylor, Ginger Rogers, Judy Garland, Dirk Bogarde and several books about Noël Coward. He had a special interest in Coward, as he was the executor of the playwright's literary estate. It was this special position that gave him possibly his greatest influence in the theatre.

Morley was one of the most prolific of West End theatre critics, holding down a portfolio of reviewing jobs for the International Herald Tribune, the New Statesman, Teletext and The Lady magazine. At other times, he wrote for the Spectator and Punch magazine. He also contributes a monthly column to the national edition of Playbill Magazine.

On the radio, he was presenter of the Radio 2 Arts program, and was known for hosting BBC Radio 4's Kaleidoscope, and Radio 2's Arts Programme and Melodies for You. As a playwright, he wrote If Love Were All, a revue which examined the relationship between Gertrude Lawrence and Noël Coward. Following runs in London and Sag Harbor, it played briefly Off-Broadway in 1999.

Mr. Morley was born Dec. 5, 1941, in Ascot, Berkshire, into a theatrical family—a subject about which he never tired of talking. He was the eldest son of actor Robert Morley and grandson of actress Gladys Cooper (he wrote biographies of both). He was named — presciently, as it turned out — after Sheridan Whiteside, a character based on outsized critic Alexander Woollcott in The Man Who Came to Dinner. It was a role his father had played. Noël Coward was a godfather, and his aunt married actor Robert Hardy.

Morley grew up in Wargrave in Berkshire, Hollywood and New York, following his father as he worked. He was educated at Sizewell Hall in Suffolk. He read modern languages at Merton College, Oxford from 1960, and became involved in student drama. He spent a year in Hawaii, teaching, where he met his first wife, Margaret Gudejko. The marriage produced three children but ended in divorce in 1990. He later married critic and TV producer Ruth Leon.

Early in life, he tried to follow his father into acting, but found little success. He returned to the profession in recent years, appearing on television in "Judge John Deed."