There are writers whose work is not published until late in their lives. Fanny Trollope published Domestic Manners of the Americans, her first of more than 40 books, at the age of 52. That was from financial necessity. Her husband had died and she had a family to support. Perhaps her son Anthony gained his discipline of writing, in his case novels, from her. He wrote his first book, The Macdermots of Ballycloran, aged 32, while working for the Post Office.

Earlier this year my first novel, North, was published. There is nothing particularly remarkable about this except that I am 68. Admittedly I had written a couple of academic books, but fiction was new to me. Now I have joined a coterie of novelists who started late: Mary Wesley, who first saw her fiction in print at 70; Charles Chadwick, whose book It's All Right Now appeared when he was 72 - it took him three decades to write; and Marina Lewycka, whose prize-winning novel A Short History of Tractors in Ukrainian was published when she was 58.

As it happened Mary Wesley proved an inspiration. I remembered that she had once said: "I have no patience with people who grow old at 60 just because they are entitled to a bus pass. Sixty should be the time to start something new, not put your feet up." For more than 30 years I had been reviewing fiction, first for the New Statesman, then for The Times, Spectator and FT. It occurred to me that I should try my hand at a novel. So, intellectually refreshed by a year of freedom, I turned my attention to writing fiction. Here, Graham Greene was my mentor. I wrote every morning until lunchtime, and only if the mood took me would I return to the typescript. Otherwise, like Dr Johnson (but only in this respect), I was available for tea or coffee. After about 10 months, North was born.

It is certainly not easy to find a publisher in your late sixties. I spent a couple of years approaching agents, finding people who liked what I had written but who doubted its marketing potential. Then I found an innovative fiction-publishing scheme, Macmillan New Writing, which took to North without hesitation, and a deal was struck.

At the same time as trying to find a publisher, I continued to write. At the present time, I have three more novels completed. The publisher David Fickling said to me with characteristic enthusiasm, "Test yourself. If you want to go on writing most of the time, if it's a habit, almost an obsession, then you are a writer in the proper sense."

I reckon I pass the test.

I wrote North because I am interested in the ways people think and behave towards one another. It is a psychological novel, a drama of suspense. Three of the main characters are young. Others are older, professionals, more sceptical and circumspect. All are caught up in the turmoil of emotion and events. The novelists whom I have admired are Greene, Henry James, Joseph Conrad and Iris Murdoch. There is no telling what their influence has been, but the agent Giles Gordon, to whom I showed the North manuscript just before his death, said it reminded him, "at different times of C.P. Snow and Iris Murdoch". I make no such claims, but pay tribute to their craft and power.

Readers should take heart. Even in your sixties, it is not too late to start a new career. A few weeks ago Joanna Trollope, a mature novelist, and Charlotte Mendelson, a young, distinguished newcomer to the art, discussed on the Today programme the contention that novelists should not start writing till they are at least 35 because they lack experience and authority. Naturally, I inclined to Trollope's point of view.

Some journalists have accused Macmillan New Writing of cheapening the publishing process for novels, likening it to Ryanair inasmuch as there are standardised conditions and no advances. The novels it publishes stand or fall on their own merits. When it came to the stage of editing the final page proofs, my editor was on sabbatical in Languedoc. I was flown down to Carcassonne to pass the pages. As my publisher put it, "North goes south on Ryanair."