Her publicist, Jacqui Graham, confirmed her death to The Associated Press.
The author of a dozen novels, Ms. Howard was best known for The Cazalet Chronicles, a five-part series that follows the fortunes of an upper-middle-class family before, during and after World War II.
The first book in the series, “The Light Years” (1990), opens in 1937; the narrative continues in “Marking Time” (1991), “Confusion” (1994) and “Casting Off” (1995).
The concluding volume, “All Change,” appeared last November.
Partly autobiographical, the novels depict a world of governesses and stately homes, but also a world of privation both material and emotional. The books have sold more than a million copies collectively and were the basis of a BBC television series in 2001.
Though some critics damned the novels as “readable,” others praised their mordant social observations and vivid depiction of the minutiae of daily lives — especially women’s lives — likening Ms. Howard to Jane Austen and Nancy Mitford.
Ms. Howard also drew wide notice in 2002 with the publication of her memoir, “Slipstream.” It told evocatively of her 18-year marriage to the novelist Kingsley Amis, in her account an angry middle-aged man.
Elizabeth Jane Howard was born in London on March 26, 1923. Her father was a prosperous timber merchant, and she was reared in what she later called “a bourgeois state of punctuality and hygiene.”
Her mother, a former Ballets Russes dancer, was, in Ms. Howard’s account, a cold, repressed woman. Jane received more attention from her father, but when she reached adolescence, she wrote, that attention turned to sexual molestation.
As a teenager Ms. Howard trained as a stage actress; at 19, to escape her parents, she married the naturalist Peter Scott, a son of the famed Antarctic explorer Robert Falcon Scott.
Ms. Howard’s youth — her husband was in his 30s — seemed to doom the marriage from the start. That she engaged in a series of affairs, one with her husband’s half brother, did not help.
She soon left her husband and their young daughter, obtained a divorce and began work on her first novel, “The Beautiful Visit.” Published in 1950, it centered, like many of her later books, on a young woman’s desire to be loved and understood.
Ms. Howard was a great beauty, with golden hair and chiseled features, and these years, her memoir recounts, were a dizzying amatory whirl — with the likes of the critics Cyril Connolly and Kenneth Tynan, the journalist Arthur Koestler and the poet Cecil Day-Lewis, father of the actor Daniel Day-Lewis.
Many lovers treated her badly. Among them, Ms. Howard wrote, were Koestler, who forced himself on her and, after she became pregnant, insisted she have an abortion, and Day-Lewis, who, she later said, wrote “a lot of rather bitter poems” in the wake of their affair.
Ms. Howard embarked on her short-lived second marriage, to the broadcaster James Douglas-Henry, she said, “because I became exhausted by people wanting to go to bed with me after half an hour.”
Her affair with Amis began after she helped organize a symposium, fittingly titled “Sex in Literature,” at which he spoke. He left his wife for Ms. Howard and married her in 1965.
Over time, Amis, who died in 1995, descended into alcoholism and unpleasantness.
“I don’t think it’s easy to live with someone who drinks too much, but in the end I couldn’t live with someone who disliked me so much as well,” Ms. Howard told the British newspaper The Independent in 2002. “You can go on living with someone who doesn’t love you, but what is really killing is someone who dislikes you.”
Though Ms. Howard and Amis divorced in 1983, she had a lasting, salubrious effect on one member of the family: his son Martin, who has credited her with securing his own future as a novelist by replacing his comic books with “Pride and Prejudice” when he was a teenager.
Ms. Howard’s survivors include a daughter, Nicola, from her first marriage.
In her 70s, Ms. Howard began a romance with a fan who wrote to her after hearing her express loneliness in a radio interview. They were happy together, she wrote — happy enough for her to lend him money.
Then she discovered he was a confidence man.
He decamped, but Ms. Howard got a novel out of the experience, “Falling,” which appeared in 1999.
Her other novels include “The Long View” (1956), “After Julius” (1966) and “Odd Girl Out” (1972).
She was also the author of a well-received short-story collection, published in 1973. Its title was “Mr. Wrong.”