Dame Penelope Keith, one of the most cherished comic actresses in British television history, died on Monday at her home in Surrey at the age of 86, ITV News reported, with her family saying she had been living with cancer.

Making Margo

Keith became a household name in 1975 as Margo Leadbetter in the BBC sitcom "The Good Life," about a suburban couple who turn their garden into a smallholding to the bemusement of their status-conscious neighbors. Margo — grand, brittle and forever defending the proprieties of suburban Surbiton — could have been merely insufferable. In Keith's hands she became something richer: a comic monument whose snobbery barely concealed an anxious, oddly touching humanity. The performance won her a BAFTA in 1977 and a permanent place in the nation's affections. Her co-star Richard Briers later credited her with much of the show's success, calling her "a marvellous actress."

To the Manor Born

If Margo made her famous, "To the Manor Born" made her a fixture. From 1979, Keith starred as Audrey fforbes-Hamilton, a widow forced to sell her grand estate and reduced to watching from a nearby cottage as a new-money supermarket magnate moves in. The sitcom drew enormous audiences and ran until 1981, with a one-off revival in 2007. Audrey, like Margo, let Keith do what she did best: play hauteur with such precision that the audience laughed with the character as much as at her.

A serious stage actress

Television fame can obscure how accomplished Keith was on stage. She had joined the Royal Shakespeare Company in 1963 and built a long theatrical career alongside her screen work. In 1976 she won the Laurence Olivier Award for best comedy performance for "Donkey's Years," and she took a second BAFTA in 1978 for "The Norman Conquests." Born in Sutton, Surrey, on April 2, 1940, she remained devoted to the county for the rest of her life.

Honors and service

Keith's standing was recognized with a string of honors: an OBE in 1989, a CBE in 2007, and, in the 2014 New Year Honours, appointment as a Dame Commander of the Order of the British Empire for services to the arts and to charity, as West End Theatre noted at the time. She served as High Sheriff of Surrey in 2002–03 and as president of the Actors' Benevolent Fund for more than three decades.

For viewers of a certain age, she will always be the woman who could deliver a withering look or a perfectly weighted line about the neighbors — a performer who found the warmth inside even her most ridiculous characters, and made a nation love them.