Lynn Redgrave, an actress who excelled in unglamorous screen roles, notably in “Georgy Girl” (1966) as an ugly duckling in swinging London, and then alternated between supporting roles and a long engagement as spokeswoman for Weight Watchers, died Sunday at her home in Kent, Conn. She was 67.

No cause of death was reported, but Redgrave had been treated for breast cancer in recent years. She explored her struggles with cancer and bulimia in books and one-woman shows, which also touched on her place in one of Britain’s greatest theatrical dynasties.

Redgrave was the youngest child of actors Michael Redgrave and Rachel Kempson and the sibling of actress Vanessa Redgrave and actor Corin Redgrave, who died April 6 at 70.

Corin’s daughter Jemma became an actress, as did Vanessa’s daughters Joely Richardson and Natasha Richardson, who died last year at 45 from injuries in a skiing accident.

Unlike her siblings, Lynn Redgrave said she did not plan on a career in the arts. She entered the family business only after her interest in horse jumping proved unrealistic. Under the tutelage of her brother-in-law, celebrated director Tony Richardson, Redgrave made a memorable film debut as a barmaid who screams “Rape!” in “Tom Jones” (1963) before moving on to larger parts on stage and screen.

Impressed by her performance in “Tom Jones,” Laurence Olivier hired Redgrave for his National Theatre Company and cast her in works by Shakespeare and Bertolt Brecht. She displayed a talent for light comedy, stealing the show as a less-than-erudite flapper in Noel Coward’s “Hay Fever,” while also taking screen roles that elevated her public recognition.

In “Girl With Green Eyes” (1964), Redgrave was the slang-spewing, man-eating roommate of a country girl played by Rita Tushingham.

Two years later, Redgrave gained 18 pounds for the starring role in “Georgy Girl,” in which she was cast as a frumpy, good-hearted soul who finds love with her father’s boss, played by James Mason.

Redgrave earned an Academy Award nomination for “Georgy Girl,” putting her in direct competition with her sister, Vanessa, who starred the same year in “Morgan!” They both lost to Elizabeth Taylor for “Who’s Afraid of Virginia Woolf?”

“Georgy Girl” was Redgrave’s breakthrough and perhaps her finest and most enduring performance, one that critics regarded as an unpretentious acting style that managed to convey vulnerability and great personal appeal.

“Georgy Girl” cemented Redgrave’s place in popular culture but had, in her own words, typecast her as “the happy lass with the broken heart.”

She played variations on that role for years to come, including the play “My Fat Friend,” which reached Broadway in 1974. She spent most of the 1980s as spokeswoman for Weight Watchers and wrote a well-received book about her eating binges, “This Is Living: How I Found Health and Happiness.”

Her acting career, meanwhile, was scattershot. One of her few bright spots was Woody Allen’s “Everything You Always Wanted to Know About Sex . But Were Afraid to Ask” (1972); she played a queen who sports an unbreakable chastity belt.

Redgrave said it took her years to come to the realization that she was happier as a character actress, which made up in variety what it often lacked in visibility.

She won strong reviews in “Shine” (1996) as an astrologer who marries and gives unconditional love to the emotionally troubled pianist David Helfgott (played by Geoffrey Rush).

Redgrave also received a supporting Oscar nomination in “Gods and Monsters” (1998), as the dowdy and religious Hungarian housekeeper to horror-film director James Whale (Ian McKellan).