The author, raised in Ilkley and famous for writing about the upper-class worlds of racing and showjumping, plans to switch her attention to football with its millionaire players and their wives and girlfriends.
Cooper, 79, who lives in Gloucestershire, said she plans to called the book Tackle, it will follow the racy theme of many of her hit titles.
“I think I only have one more novel in me. I am going to be 80 in February,” she said.
Cooper, a long-standing football fan, said the plot will see the caddish Rupert Campbell-Black take over a club and the book will follow the fortunes of the team’s players and families.
She follows the fortunes of Gloucestershire-based Forest Green Rovers, who are owned by Ecotricity millionaire Dale Vince and play in the Nationwide Conference.
She even went to Wembley to watch them lose out on promotion to the Football League last season.
“You make more money out of football,” she said.
“I love football. As a child our cat supported Scunthorpe and our golden retriever supported Motherwell. We supported Leeds United because we lived in Yorkshire.”
Cooper told the Cheltenham Literature Festival she had ideas for other books but her most recent novel, Mount!, was years in the making.
“I want to write about football and I also want Dora Belvedon to save a local newspaper,” she said.
“I am very serious about local newspapers as they are the guardians of our morality and they dig around in places like Stroud and Cheltenham and find all sorts of things happening.
“They are wonderful and they are just closing down like mad and it is so sad.”
Cooper, who was in conversation with broadcaster Clare Balding said she shuns computers and still writes her novels on an old manual typewriter.
“I have tried to learn,” she said.