While struggling to write the novel that would transform her career, she discovered the country pile that would prove inspirational

Being a very horsey little girl, I always dreamed about writing a novel about show jumping, but I didn’t get down to it until I was in my 30s, in 1972, when my publisher gave me an advance and my husband, Leo, and I moved to Putney in London. Ten years later, shamefully, I had made little progress, finding it difficult to describe the changing seasons in London and having only riding school horses to interview.

Then, in May 1982, Leo, I and our two mongrels, Mabel and Barbara, were invited to Longleat for the weekend. Our host, Alexander Thynn, the Marquess of Bath, was an adventurous artist and we were excited to find ourselves sleeping in the Kama Sutra room. This had a rhino horn sticking out of the bedhead of a large four-poster, a mirror on the ceiling and numerous couples in different sexual positions painted around the walls.

After an evening of carousing, we collapsed into bed, not realising that Barbara was stretched out between us. At dawn, catching sight of herself in the mirror overhead, she went into a frenzy of yapping and roused the entire household. Later, we took our hangovers on a sponsored dog walk for charity around the estate. Passing the safari park, Barbara refrained from barking at zebras, rhinos, giraffes and several lions.

Over a splendid lunch, during which I said that Leo and I were thinking of moving to the country, someone mentioned a heavenly house in Gloucestershire, which was just coming on to the market.

Leo viewed it the following weekend and came back very pale. He didn’t want to pressure me, but he had fallen totally in love with the house, which in the 14th century had been a monks’ dormitory, with the monastery itself situated in a nearby village. A week later, I went down and fell equally in love. The house is made of Cotswold stone, which turns platinum blond in sunlight. Overlooking a valley of trees and fields, it has a halo of bluebell wood behind.

Four months later, we moved in. With the ravishing countryside all round, a horse in nearly every field and a thriving local hunt, I was inspired to finish my show-jumping novel, Riders, in less than two years. Our house and land (in a much grander form) became the setting for the home of my ongoing hero, Rupert Campbell-Black.

I am not sure how much the monks would have approved of Rupert’s goings on, but I am still as much in love with the house as ever.

Mount! by Jilly Cooper is out now