I remember one of these governesses, Miss Hussey, because she stayed two years, which was a record. She was an anonymous-looking woman with brown hair and a beige face. She wore no make-up, as it was against the rules, and she dressed in tweeds. She had been in India and used to tell us about it until we yawned with boredom.

My mother was my first teacher. She taught us all to read and spell and then, when we were seven, we went into the schoolroom to be taught by the governess. I did go to boarding school in Oxford for two wickedly awful days, but I didn’t like it. I fainted in geometry and was sent home, thank God.

I learned much more from my family and people like the groom, the blacksmith, the cowman and the gardener, than I ever learned in the schoolroom. My best friend and one of my best teachers was Charles Hooper, our groom. He had suffered terribly from shell shock in the First World War and used to lose his temper with my sisters, who weren’t good riders, but he was always kind to me because I adored the horses and everything to do with them. I learned from him about life and death and the seasons; he showed great patience with me. I suppose I was his favourite because I was the youngest and interested in what he was interested in.

I also adored the blacksmith, though I’m afraid I can’t now remember his name. He was a lay preacher and very clever. He wasn’t educated in the conventional sense, but he knew everything. From him I learned patience as I watched him work with the iron, shoeing the horses. He would try to talk to me about religion sometimes, but I was only interested in the animals.

Constable, the cowman, taught me how to milk cows and I was allowed to put my finger in the cream in the dairy, something that is taboo now. My mother kept some beautiful cows and I was fascinated by the cowshed and everything that went on there.

Most of my sisters’ friends turned out to be intellectuals, such as Waugh, Acton and Betjeman. The two men with the best manners I have ever seen were Harold Macmillan and Sir Oswald Mosley, my sister Diana’s husband. You could learn a lot just by watching them. My husband is incredibly clever. His great interest is politics and he is completely brilliant at it, always 10 jumps ahead. I’ve learned a lot from him. And my father taught me a certain amount about running an estate, which has been useful at Chatsworth. He was a real countryman and understood the people who worked the land.

These days, I think, children’s lives are ruined by exams. They are such a cause of unhappiness. I suppose there has to be a system of employing people by exam results, but all they tell you is what has been bunged into their heads. They don’t tell you if they are honest, can get on with people, are truthful, show discretion, cheerfulness and punctuality. Look at somebody entirely self-taught such as Joseph Paxton, who was the son of a gardener. He was made head gardener here at 23, went on to be a railway engineer, built the Crystal Palace and became an MP. I consider people like him to be clever, not people who have passed exams.

Deborah, the Duchess of Devonshire, was talking to Pamela Coleman

THE STORY SO FAR

1920 Born in London, Deborah, the youngest of the Mitford sisters (Nancy, Pamela, Diana, Unity, Jessica), daughter of Baron Redesdale

1941 Marries Lord Andrew Cavendish (later Duke of Devonshire)

1972-41985 President, Royal Smithfield Show

1982 First book published (The House: a Portrait of Chatsworth)

1990 Launches annual Countryside Day for Schools at Chatsworth; becomes honorary fellow of Sheffield City Polytechnic

1996 Honorary doctorate, University of Middlesex

1998 Honorary doctorate, University of Sheffield

1999 Created Dame Commander of the Royal Victorian Order April 2002 Publication of Chatsworth: the House (Frances Lincoln, pound;29.99); lecturing at Cheltenham Festival of Literature, tomorrow 11.30am (bookings 01242 227979)