illy Cooper, the British author of novels such as “Rivals” and “Riders” whose 1980s bestsellers were a blend of sex, satire and British snobbery, has died aged 88, her agent said in a statement on Monday.

Cooper sold 11 million copies of her books in Britain alone. From the mid-1980s, her raunchy novels depicting the romantic adventures of an upper-class set of characters in the fictional county of Rutshire gained increasing commercial success.

Last year, “Rivals” found a new generation of fans when it was made into a series for Disney+. Sales of books first published decades before shot up once again, as the themes of adultery and class rivalry thrilled younger audiences.

“You wouldn’t expect books categorised as ‘bonkbusters’ to have so emphatically stood the test of time but Jilly wrote with acuity and insight about all things,” Cooper’s agent, Felicity Blunt at Curtis Brown, said in the statement.

‘FAR LESS BONKING NOW’

Born in Essex in 1937, Cooper was a newspaper columnist for the Sunday Times in the 1960s, commenting on marriage, sex and household chores, before she started writing novels in the 1970s.

It was not until Riders in 1985 that she had her breakthrough. At the centre of the story was Rupert Campbell-Black, a handsome, ruthless showjumper and womaniser, who lives on his family’s manor house in Rutshire.

“There’s far less bonking now. People are so serious. I think we need more joy,” Cooper said last year.

Rutshire was inspired by Gloucestershire, where Cooper moved in the early 1980s. Amongst her social circle in that part of western England was Camilla Parker Bowles, now Queen Camilla, following her marriage to Prince Charles in 2005.

Speaking on a podcast last year, Cooper was asked about Camilla’s first husband, the army officer Andrew Parker Bowles.

“He’s been a great friend for a long time… so he’s very like Rupert. He’s beautiful and blond and stunning,” she said, referring to the Rupert Campbell-Black character of her novels.

Cooper wrote more than 40 books, many of them produced in a summerhouse at the bottom of her garden while she listened to classical music.

She died after a fall on Sunday, her agent’s statement said. A dog-lover, she married Leo Cooper, a publisher of military history books, in 1961 and they had two children. He died in 2013.

Filming for the sequel to “Rivals” began earlier this year.