Some events stay with us for a lifetime. One night, when he was a child, William Boyd was the passenger in a car driven by his father. The family lived in Nigeria where their existence was, for the most part, only peripherally affected by the civil war then convulsing the country.

On this occasion, however, Boyd senior chanced upon a roadblock manned by aggressive, drunk soldiers. His son can still taste the mingling of fear with excitement as the militiamen pointed their rifles in the windows.

"I remember thinking `this could all go horribly wrong'," he recalls now with a dry laugh. "My father dealt with the situation very well and they let us go, but for a moment I got a glimpse of how thin the ice was. In any war zone you get that feeling of life's inherent unpredictability and fragility. It's something I've been aware of from very early on."

The random nature of life is a common theme in Boyd's fiction. Ever since his first novel, 1981's A Good Man In Africa, the author has invented characters whose triumphs and disasters result from chance and chaos. The pattern continues in his newly published book, Any Human Heart.

The novel, Boyd's eighth, takes the form of a journal by Logan Mountstuart. As a young man, Mountstuart is lauded as a writer and enjoys international success. But a series of malignant twists of fate sour his life.

He goes through three marriages, and falls into alcoholism and obscurity. By the 1970s he is a pitiful figure, living on dog food and scraping together money by selling revolutionary newspapers.

Mountstuart's adventures give Boyd licence to populate the book with some of the twentieth century's leading literary figures. His hero meets Ernest Hemingway during the Spanish Civil War, makes the acquaintance of James Joyce in Paris, and develops an intense dislike for Virginia Woolf.

Boyd first created Mountstuart for a short story that appeared in his 1995 collection, The Destiny of Nathalie X. The character is loosely based on a now-forgotten author whose legacy Boyd has begun to champion. "If we were in 1923, the one name on our lips would be that of William Gerhardi, the English Chekhov," he says excitedly.

"Edith Wharton wrote an introduction to his first novel. Evelyn Waugh said, `I have talent; he has genius.' He published his last book in 1940 and died in 1977, so there were 37 years of silence, poverty and obscurity. He is," Boyd concludes with an awkward laugh, "a great case study in how everything can go completely awry."

Boyd's decision to present the novel as Mountstuart's journal was carefully considered. He has played around with the genre in previous books, most notably in his 1998 spoof biography, Nat Tate. The idea of a journal appealed to him because, he says, "it is the form which most closely replicates the experience of living."

"The journal form unspools very like our lives do," he explains. "There is no hindsight, no `little did I know' perspective. Other ways of writing -- the novel, the memoir, the biography -- are very artificial because they are very shaped. Reading them, you know that the story has been smoothed and polished. Life is not like that. Life is random, messy, full of loose ends and unexplained things."

Boyd's own life has had its own small dramas. He was born in Ghana in 1952 to Scottish parents who had come to Africa after the Second World War. He retains the clipped accent of the British colonial class, but none of the arrogance -- his manner is polite and friendly. He remembers his African upbringing fondly, at least up until civil disturbances began to intrude on his world. "It was a kind of idyll. My father was a doctor and my mother was a teacher, but the life they led in Africa bore no relation to the lives led by their equivalents in Britain. We had a big house, and we had a cook, a houseboy and a gardener. As a boy I used to go to the beach a lot. For my parents I think it got harder and harder, but my memories are of an amazing time in an amazing place."

The idyll was soon interrupted. Almost all children from Boyd's background were sent back home to a British boarding school. He was despatched to Gordonstoun in Scotland. The harshness of the school system made a profound mark on him.

`WH Auden said that any child who has been to boarding school understands what it is like to live in a fascist state," he comments wryly.

"It is the powerful who dominate your life. People would come in and trash your room, steal whatever you had to steal, and you could do nothing about it. There were lots of beatings. It was the norm, but I look back on it and it seems a crazy way of educating a young person."

By the age of 17, Boyd had vague thoughts of becoming a writer. He began to work seriously towards that goal at university. He graduated from Glasgow University with a degree in English and Philosophy, and moved on to Jesus College, Oxford, to do a PhD. "I was writing stories while I was at Oxford," he says.

"First I won second prize in a competition judged by Iris Murdoch. Later, I won third prize in a competition judged by Roald Dahl. Then I looked at my trajectory and thought I should stop," he jokes.

The struggle for recognition was long and trying. Boyd completed three novels; none was published. He made his living in academia and from occasional exploits into literary journalism.

"My debut novel was actually my fourth novel," he says. "I often say to young writers who have written a novel and can't get it published, `well, write another one'."

For the past 20 years, Boyd has enjoyed a reasonably successful career. His finely wrought books have won him a substantial following, although he has never acquired the A-list status some critics think he deserves.

This doesn't seem to bother him much, though. He is a craftsman above all else. He doesn't have much tolerance for the tantrums and self-indulgences that other writers engage in.

From the beginning of his career he has advocated hard work and diligence, asserting that notions like writer's block are self-fulfilling prophesies.

"I know some writers enjoy the invention, but find the writing an endless night of the soul," he once said. " I don't. I think that if you can earn your living writing fiction it's very agreeable."

Boyd does not get his professional satisfaction from commercial success or the fawning of fans. He simply thinks he has become a better writer as the years have gone by. "I don't disown any of my books," he says.

"Many readers will say that their favourite book is one from quite a long time ago. But I would say that the craft and skill of writing are things that you get better at the longer you write. You learn all sorts of little tricks.

"This book is me firing on all cylinders," he concludes. "This is the best that I can do."

Any Human Heart by William Boyd is published by Hamish Hamilton, priced stg£18