Margaret Tyzack, 79, actress on British stage, Broadway

She won another Olivier two years ago as Mrs. St. Maugham, the haughty grandmother of an unruly granddaughter, in Enid Bagnold’s 1950s comedy “The Chalk Garden.’’ Charles Spencer, writing in The Guardian of London, called the role “perhaps the greatest performance of her long career.’’

Her Mrs. St. Maugham was “at once imperious, funny, and spiteful,’’ Spencer wrote. “Her acting is an object lesson in comic timing, and she delivers the epigrammatic dialogue with superb panache.’’

Ms. Tyzack appeared twice in featured roles on Broadway. In 1983, as Countess of Rousillon in “All’s Well That Ends Well,’’ she was nominated for a Tony. Her next Broadway role, in 1990, was Lotte Schoen, an official of the Preservation Trust who is the foil to a flamboyantly eccentric tour guide (played by Maggie Smith), in Peter Shaffer’s comedy “Lettice and Lovage.’’

That production appeared first in London and was almost kept from opening in New York because of union rules that require special permission for the casting of foreign actors in Broadway productions, permission that is usually granted only to international stars of indisputable singularity or box-office drawing power.

Smith refused to appear on Broadway unless Ms. Tyzack joined the cast, arguing that their chemistry and Ms. Tyzack’s gifts fulfilled the requirement of singularity. Actors’ Equity finally agreed. She won a Tony for it.

She first came to prominence in 1967, when she appeared as Winifred, sister of Soames Forsyte, the lead character in “The Forsyte Saga,’’ a 26-week BBC series that traced the fortunes of an upper-middle-class British family through 40-some years on either side of the turn of the 20th century.

A hoity-toity soap opera about hoity-toity people, it was hugely popular; English churches were said to have rescheduled Sunday evening services so that congregants would not have to choose between worshiping and watching.

Acquired by US public television in 1969, it proved equally popular in the United States, although without reports of religious disturbance.

Ms. Tyzack was born on Sept. 9, 1931. She attended the Royal Academy of Dramatic Art and began her professional career in the early 1950s at a repertory company in central England.

“We weren’t spoiled or indulged,’’ she said in a 2009 interview. “It was very hard work, and the paying customer came first. It was expected that they would hear every word, even if they were sitting far from the stage. If you were warned for inaudibility on Wednesday and still couldn’t be heard on Thursday, you’d be sacked on Friday. You had to learn quickly.’’

She appeared in a handful of movies, including two directed by Stanley Kubrick, “2001: A Space Odyssey’’ and “A Clockwork Orange.’’ More recently she appeared in Woody Allen’s “Match Point.’’