British author Jilly Cooper, known for her bestselling risqué novels including “Rivals” and “Riders,” has died at age 88, her agent and family said Monday.

A statement from her family said that the author’s “unexpected death has come as a complete shock.”

Cooper was best known for her books in “The Rutshire Chronicles,” which portrayed the sex lives and excesses of the well-off, horse-riding set in 1980s England. The books sold millions of copies in the U.K. alone.

One of the books, “Rivals,” was turned into a hit Disney+ TV series last year starring David Tennant and Alex Hassell.

“The privilege of my career has been working with a woman who has defined culture, writing and conversation since she was first published over fifty years ago,” her agent, Felicity Blunt, said in a statement.

“Jilly will undoubtedly be best remembered for her chart-topping series ‘The Rutshire Chronicles’ and its havoc-making and handsome show-jumping hero Rupert Campbell-Black.”

Born in 1937, Cooper cut her teeth in journalism at a local newspaper in Brentford, covering everything from parties to soccer.

Her big break occurred in 1969 when The Sunday Times published a story on being an ”undomesticated” homemaker. It resulted in a column that lasted over 13 years. She went on to another column in the The Mail On Sunday for five years.

Her first book “How to Stay Married” was published in 1969.

Cooper’s many fans included former British Prime Minister Rishi Sunak, who said the books offered “escapism.”