BEFORE KEN Follett became a writer of bestsellers he dreamed of creating a hero like James Bond. Although he tried, he says, he never quite managed it. But while Ian Fleming's cocktail of glamorous violence and gratuitous sex eluded him he managed nevertheless to forge his own brand of thriller, most notably with The Eye Of The Needle, his third novel, published in 1978, when we was just 27.

Since then, Follett has never been far from the top of the charts. Not for him the Holy Grail of posterity or literary acclaim. Like Stephen King and John Grisham, his success is measured in sales of industrial quantity. He shows no shame, for instance, in acknowledging the influence of the likes of Alastair Maclean or Harold Robbins. As for Dan Brown, he will not hear a word said against him. Apropos The Da Vinci Code he says: "I really loved it. I think it's a little masterpiece."

Sincerely?

"You do have to put aside the thought that will occur to you that it's not really plausible that people would kill one another over whether or not Jesus had a baby with Mary Magdalene," he concedes. "But a lot of books require an effect of that kind."

The same, one suggests, might be said of Ian McEwan, whose latest novel, On Chesil Beach, requires us to believe that a couple who fail to consummate their marriage on their wedding night would split up as a consequence. But the allowance Follett is prepared to make for Brown does not hold for McEwan. "I think that's Ian McEwan's terrible shortcoming. There's always a moment like that in a McEwan novel where you think: no, that wouldn't have happened."

Follett's job, however, is to so engulf readers in the story he's telling that they turn the pages almost without noticing they're doing it. Everything he does, he says, is secondary to the plot. Thus out of the window goes subtle characterisation, fine prose and any words that would tax a 10-year-old. His latest novel, World Without End, is an exemplar of his style. A sequel to The Pillars Of The Earth, which sold in multiple millions, it's set in 14th-century England and gallops along like a thoroughbred at Ascot. No attempt is made to write in period language. Instead characters speak as if on a daytime TV soap, and paragraphs rarely add up to more than a few lines.

Follett is in Glasgow for a day of interviews. He has silvery bouffant hair, wears a sharp suit, the trousers of which are kept aloft with power braces, and flashes cufflinks which are marked K and F. He is married to Barbara Follett, the Labour MP, one of Blair's original babes. That, though, was then. These days, the Folletts are no fans of the former PM and have thrown their lot in with Gordon Brown. Not that Ken Follett is keen to talk about politics. Perhaps it is too painful. Or maybe it just bores him. One senses he much prefers the middle ages, bubonic plague and all, to 21st century Westminster.

It took three years, he says, to produce World Without End: one to research it, another to write it, and yet another for the rewrite. Noting that he employed a New York-based research company to assist him, I ask what it could do that he couldn't do for himself. The short answer, it seems, is find experts such as Sam Cohn, Professor of Medieval History at Glasgow University, to act as consultants and offer expert advice.

Take The Hammer Of Eden, he says, by way of example. For that book, a researcher was asked to find a woman FBI agent "preferably based in San Francisco", root out a seismologist who could tell him about the San Andreas fault and put him in touch with the governor of California.

"I flew in and did all of that in a week. It meant I had the time to drive around and look at locations. I could do the legwork myself but it would take an awfully long time and there'd be no point. But I always do the interviews. He the researcher never does any interviews or reading."

The Pillars Of The Earth and World Without End marked a departure for Follett, being set in an era beyond his personal ken. Normally, such books would be categorised as historical novels but it is not a genre Follett wants to be seen dead in. Why not?

"I didn't really think of them as category historical novels because I didn't write them for people who go to the library or bookshop looking for a historical novel. I didn't think about it that way at all."

But won't people think of them as historical novels anyway?

"Sure. Absolutely. But we're not selling these books to that market, as it were, because it's too small. If I had thought that World Without End would only be read by people who like historical novels I wouldn't have written it."

Has he ever harboured a desire to write literary fiction?

"You're talking about a kind of novel I don't want to write and probably couldn't."

Why not? Does he not have the inclination or the ability? "It's hard to know the difference between those two things: no inclination and not having the ability. Because they sort of go together, don't they." Well ...

"I would not want to What I like are strong stories, plotted stories with constant story turns. That's what I like to read and that's what I like to write. I certainly haven't got the inclination to write any other kind of novel and I doubt whether I could, but I'm never going to find out."

What he doesn't like, he says, are novels such as John Banville's Booker-winning The Sea. "I thought the prose was so overwrought. And to no purpose. I would not use a particular word or phrase or play with words or write in that intense way for its own sake. The prose is a means to an end for me. Now I think in a book like The Sea the prose is not a means to an end. It is the purpose. And it had better be because the story's crap."

Thin, perhaps, but crap?

"No, crap is the word I am looking for here. You know I just hate stories where some kind of sexual liberation has to be followed by some awful punishment. Stories where as soon as the frustrated housewife actually gets a shag, her children have to die. I find that so tiresome. What's the other book that does that? That woman writer, Roy "

Arundhati Roy, author of The God Of Small Things?

"Yes. That book. The same thing happens in that book. As soon as the poor woman actually got some bloke in bed her children were drowned in a river. It just gets on my nerves."

World Without End is published by Macmillan, £20