I didn't intend to teach. After I'd taken my degree, I started some research on the Revocation of the Edict of Nantes, but in the November I found they wanted someone to teach temporarily at Harrow. So I came here in 1953 with the marvellous idea that in the evenings I could write. But I found teaching was a busier occupation than I imagined, and I've been here ever since.
In the Fifties Harrow was much like the pre-war Shrewsbury I'd attended. There were no exeat days. If parents didn't come to take them out to tea, the boys might not see them at all until the holidays.
I think the relationship between boys and masters is more relaxed than it used to be, though it wasn't so formal even then: I would go for bicycle rides with pupils even in the earliest days. Somehow I managed to find time by 1966 to finish a book - Seventeenth Century France - which is still in print with John Murray.
In 1967 I married and became a young housemaster in Headmaster's house. Melisa, my wife, really has been the heroine of the story. She was from New York, an editor at John Murray, who came down to the school partly because she published the School Science Review and partly because someone invited her on the grounds that there were 'lots of marvellous bachelors' at Harrow. We met for the first time then. After meeting three more times, we got engaged. She gave up her job. At that time it was difficult to combine the duties of housemaster's wife with outside work.
In the Sixties there was a recognisable change in the school. It was the height of the pop decade . . . the Beatles. Boys started wearing rings and looking like pop stars. They wanted to be different, and I saw a great deal that was good in that. But it was a difficult position trying to hold on to what was important, the feeling of community. The housemaster has to take over the role of parent, and the parents expected us to have a fairly strict regime. The whole business of caning had been taken for granted by my generation. I stopped that in my house. It suddenly became unthinkable: a humiliating thing to do.
The number of divorced parents increased, but I didn't find their sons were less stable. Some of the most difficult boys came from the happiest homes: naturally they wanted to get back to them.
I spent six years in Headmaster's house. I would breakfast with my family - we have four daughters - then there would be some teaching, writing to parents. Then lunch with the boys. Each house had a cook until 1976, when the school started eating together. You kept an eye on their manners.
There are days and weeks when you work round the clock. It's a total commitment. The headmaster has to rely on the fact that over the weekend about one third of the staff will be taking games and running societies. I've been lucky in that I've always been able to concentrate. My friends say I wrote my books on the backs of envelopes. I published a Life of Richelieu in 1972, then The Making of Modern Europe in 1985.
After six years in Headmaster's house, in 1973, I became housemaster of The Grove - an 18th- century building where Sheridan had lived. Everyone says, how beautiful, but remember, you had to share it with 70 boys. At the end of our first year, soon after our youngest daughter had been born, we had a very bad fire. All the top floor went up, and the water tanks came down through the house. Melisa says it was a literal watershed for her, she had grave doubts about whether she wanted to come back to live in it. But we did. It was a brave decision of hers, I think.
The school has relaxed in some ways. There is shirt-sleeve order now for hot weather. But the famous hat is still there. I rather like it, and the boys do on the whole. And Sunday dress, the old-fashioned tails, they still wear them. The boys go out far more: home, to London, to do community service.
The demands of exams, of course, have changed enormously. There's far more awareness of the need to look at sources and documents. I'm very optimistic about history A-level. In history GCSE the syllabus can lend itself to short cuts and slick answers, but it can be stimulating.
One or two of the boys I have taught have become dons, for example Richard Fletcher, a leading Anglo-Saxon historian. There's a lieutenant-general, Charles Guthrie, who was in one of the first classes I took. It's unbelievable when even the generals start to look young.
We have a small farmhouse in Herefordshire that we have been doing up for 20 years: that has been our real home, and that is where we'll live. And we'll travel. There are lots of things I've been waiting to do. I'm working on a book on Cardinal Mazarin now, and that should appear in two years' time.
I was paid more or less the same as in the state sector, with an allowance for the education of my daughters. But I think I've been very fortunate to find a job that has been a happy pursuit. Fitting the Victorian idea of 'godliness and good learning' in with the world of GCSEs has been a fascinating challenge.
Education: School's out for ever: the teachers' story