LONDON (AP) — Mystery writer Ruth Rendell, who brought psychological insight and social conscience to the classic British detective story, has died at the age of 85.

Publisher Penguin Random House said Rendell — best known for the Inspector Wexford series of novels — died Saturday morning in London. The cause of death was not announced, but Rendell had suffered a serious stroke in January.

Gail Rebuck, chair of Penguin Random House U.K., said Rendell had been "an insightful and elegant observer of society" whose work "highlighted the causes she cared so deeply about."

"Ruth was a great writer, a campaigner for social justice, a proud mother and grandmother, a generous and loyal friend and probably the best-read person I have ever met," Rebuck said.

Rendell was one of Britain's most popular crime novelists and wrote dozens of books, including many under the pen name Barbara Vine.

She was also a major influence on other writers. Stephen King tweeted that her death was "a huge loss."

Born Ruth Grasemann in London in 1930, Rendell began her career as a journalist on a local newspaper, but had to resign after reporting on a sports club's dinner without attending — thus missing the moment the after-dinner speaker dropped dead.

Rendell told The Associated Press in 2005 that she started her literary efforts by writing some "very bad" novels that were never published. After these false starts, she found that "suspense and a sort of tension and a sort of mystery was my forte."

Once she found her way, Rendell produced novels at an astonishing pace — more than 60 books over four decades, including 20 featuring the liberal, literary small-town detective Chief Inspector Wexford. The Wexford books were made into a popular TV series, "The Ruth Rendell Mysteries," which ran for more than a decade from 1987.

Her output also included chilling, elegantly plotted psychological mysteries and the thick multigenerational thrillers published under the Barbara Vine pen name.

A lifelong socialist, Rendell anchored her thrillers in a distinctly modern landscape, introducing issues including environmentalism, politics, mental health and celebrity culture. She brought to the classic mystery a psychological depth that gave readers unusual access to the emotional makeup of seemingly ordinary people capable of foul deeds.

The author was appointed to the House of Lords by Prime Minister Tony Blair's Labour government in 1997, becoming Baroness Rendell of Babergh. She took the work seriously, attending afternoon sessions in Parliament after she had finished her morning writing. She was especially involved in the fight to stop female genital mutilation, Rebuck said.

Her friend and fellow mystery novelist P.D. James, who died last year, also sat in the Lords, as a Conservative.

Rendell lived for years in the scenic Little Venice neighborhood of London, surrounded by canals and colorful houseboats. But the pleasant environment did not alter her hard-eyed view of human nature.

"I don't think the world is a particularly pleasant place," said Rendell. "It is, of course, for some people. But it is a hard place, and I don't think it's being cynical to say that."

Rendell was conscious of the strong feelings many of her readers had for Wexford, her most famous creation.

"With a series character like Wexford, people do regard him as a real person that they become extremely attached to," she says. "Women have written to me over the years and said that they were in love with him and would I kill his wife because they'd like to marry him."

Rendell told The Independent newspaper in 2014 that her personal hero was South African Bishop Desmond Tutu "because he's such a good man and he's had a hard life and always looks so happy."

The same year, she told an audience at the Cheltenham Literary Festival that she shied away from writing about child murder for fear that writing about it might in some way show criminals how to do it.

"I would rather not be involved, rather not be responsible," she said.

The same concerns kept her from writing about cruelty to animals, she said.

She would spend long hours walking in London, taking in the sights and conversations and forming impressions for her book, and also was an opera fan.

Rendell's husband, journalist Donald Rendell — whom she married, divorced and remarried — died in 1999. She is survived by their son, Simon.

Her final novel, "Dark Corners," is due to be published in October.

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Associated Press Writer Gregory Katz contributed to this report.