UNLESS you are one of those writers who churns out books like tweets there will be times when years may go by when little is heard of you.

Kazuo Ishiguro is that kind of novelist. Since he first appeared on the radar in 1982 with A Pale View of Hills, he has paced himself like a prize fighter who only steps into the ring when there is a rival worthy of him. Over the past three decades Ishiguro, who was born in Nagasaki in 1954 and arrived in Britain six years later, has published just eight books, each of which lives long in the memory and repays rereading.

Memory, of course, is one of his constant themes, how we live with it and how we often try to erase it. For Ishiguro the past is not so much a foreign country as a familiar place from which we can never escape however hard we may try. His latest novel, his seventh, is The Buried Giant, which comes after a ten-year hiatus, following Never Let Me Go. Here, too, memory is central. "You would have searched for a long time for the winding lane or tranquil meadow for which England later became celebrated," it begins. As opening sentences go, it is perfectly balanced, beautifully nuanced and freighted with meaning. Instantly, you know you are in the hands of an author who won't put a word in print until he's satisfied that it is capable of doing its job.

On first impression, The Buried Giant would appear to mark a dramatic departure for Ishiguro and it has certainly stunned some observers, not least because it features what he describes as "ogres and all" and adopts many of the tropes that are the hallmark of fantasy fiction. Game of Thrones, Lord of the Rings, The Once and Future King, Arthurian myth, Robin Hood: Prince of Thieves and Dungeons and Dragons are just a few of the references with which reviewers have attempted to convey a sense of it.

I catch up with Ishiguro by phone. He is in Manchester, of that he is certain. He is less sure what day it is, however. It is the start of a promotional tour which will take up several weeks, with one town blurring into another. This morning he has already been on the Today programme and breakfast TV, where a fellow guest was Frank Sinatra Jr. "I'm taking every day as it comes, like an alcoholic," he says. He will only be north of the border briefly, though over the past couple of years he has spent many hours in Glasgow where his wife, Lorna, is from. "I've got to really like Glasgow," he says. In particular, he was much taken with the Hyndland bookshop, where he and Lorna would go when not visiting her ailing mother. "Do you know it? It was a lifesaver for us in the bleaker moments."

What first struck me about The Buried Giant was its tone. It is the thread that links all of Ishiguro's books, including The Remains of the Day, which in 1989 won him the Booker Prize. Tone is not something of which he is particularly conscious, he says. "I'm just trying to tell my story as best I can and in a way the tone is the one that's natural to my voice. It's interesting that you should stress the continuity with what you just said because a lot of people have been startled by the surface of it. For me it doesn't feel like a big departure. I'm on my same territory. My mind is always more focussed on how I make a scene work, how I convey a certain emotion. I suppose it's a bit like when you listen to somebody else's voice, they're not so aware of the characteristic tones. In a way I'm quite happy that there's something that comes through that links this book with the other books."

The setting for The Buried Giant is primordial England, after the Romans have departed and the civilisation they imported has disintegrated. The population is comprised of Saxons and Britons who're at each other's throats. King Arthur is no more but there are still a few of his knights roaming the countryside, their armour rusting, their glory days gone. There is, moreover, an ominous icy mist hanging over the rivers and marshes, "serving all too well the ogres that were still native to the land."

The novel's plot involves an elderly couple of Britons, Axl and Beatrice. They are on a quest to find their son who they think lives a few days' walk from their village. Or so they believe. With the coming of the mist, their memories are muddled, as are those of the people they live among. The narrator is at pains to point out the difference between the England of popular perception and the featureless one through which Axl and Beatrice have elected to walk. "Never mind the possibilities of perishing in bad weather: straying off course meant exposing oneself more than ever to the risk of assailants - human, animal or supernatural - lurking away from the established roads."

Finding the right setting and period for the novel, acknowledges Ishiguro, proved troublesome. Though he always knew the story he wanted to tell, he had to figure out a way to make it work. "For a long time I had this story without a particular setting in which to put it down in. I knew it was about some society that had buried certain dark memories about a generation back. I wanted that contrasted with an ageing couple who had been married a long time and they faced the same questions, about do they want to remember something in their pasts or do they want to leave them buried."

The mysterious mist was the device which offered him a solution. But there was still the question of where and in what era the action might happen. He had faced a similar dilemma in Never Let Me Go. In it, he imagined an alternative, future reality in which Norfolk, where Ishiguro attended university, stands for England. In The Buried Giant, he wasn't sure whether to set it in the past, present or future or in a real, named country or somewhere unidentified and unspecified on any map known. History offered him an abundance of options: France after the Second World War, Rwanda, Yugoslavia, all places where memory is both a curse and a blessing, where remembering and forgetting are both desirable and intolerable.

"I did actually toy with contemporary settings or recent historical settings," says Ishiguro. "But then I just thought I'm going to end up writing something people will see as a very journalistic book, that's actually about these issues rather something more universal. I was trying to find a landscape and I ended up thinking I'll need to do another sci-fi-ish thing, like Never Let Me Go, or I could retreat into the distant past so people will see this as a kind of metaphorical landscape that could be applied to all kinds of contemporary and historical settings."

The real landscape he had in mind was that of Iceland which he visited some years ago. Geographically and visually, he says, it's weird. And while the people are in many ways highly sophisticated and hyper modern, they are still influenced by myths, "which to some extent they're almost embarrassed about." For instance, roads which could follow straight lines have been made to twist and turn to avoid elves' communities because when previously they went through elvish villages there were a lot of accidents. Ishiguro laughs at the thought but the incongruity clearly appealed to him. His own background is similarly one of contrasts.

"I've come at this from the samurai stuff I grew up on," he says, "and westerns, particularly the later westerns of people like Sam Peckinpah. You know, when they get a bit elegiac. Pat Garrett and Billy the Kid and The Wild Bunch or John Wayne in The Searchers and True Grit. Those ageing gunfighter things. The portrait of Sir Gawain in The Buried Giant owes something to them."

Last year he turned 60 and, given his rate of production, says he must now consider carefully before embarking on projects that will take several years. He keeps a notebook in which to jot ideas. He likes to write down just a few lines which, like dough, will grow over time, either into a novel or a film. He continues to be fascinated, he says, by what happens when he writes these lines down and they begin to interact. What he's looking for is energy, chemistry, "some huge forces". It is the acorn from which a mighty oak will grow.

"Particularly as I grow older, I'm conscious that I may not write that many more books. There seems to be an awful lot of books out there and I've already myself written a certain number of them. There's no problem in terms of quantity. If I'm going to write a novel it has to be something that's a bit different, that's going to change the landscape a bit, to contribute something a little bit fresh and new...Why the hell are we spending all this time and effort trying to add to this overwhelming mountain of stuff?

"I think the only answer we can come up with is because of the possibility that the next book is going to be in some little way unique. That's the only justification for adding to the pile. Yes, it's just another book in a way, but you've got to be able to say there is a little chance that my book is offering an experience that you won't get in all the other books. And if there isn't that chance I don't see much point in going about it."

The Buried Giant is published by Faber & Faber, priced £20