Many of your earlier books are retellings of folk tales and legends. What led you to write a story set at the turn of the 13th Century?

When I was a boy, I took over the shed at the bottom of the garden, and displayed fossils and potsherds and coins in it, and proudly called it my 'museum'. I charged people to come in, and my most prized possession was a Saracen shield dating from the Crusades. Since then, I have been absolutely fascinated by the medieval world - its passion and piety and color. It's true that much of my work has been with traditional tales, but actually my first two books, Havelok the Dane and King Horn, were novels based on medieval Romances.

Would the stories of King Arthur, interwoven into this narrative, have been familiar to a boy living in the year 1200? How did you decide which of the Arthurian stories to have the Stone reveal to Arthur de Caldicot?

The reason for setting the trilogy at the turn of the 13th century is that this is when stories of King Arthur were just, but only just, becoming known in Wales and England. King Arthur is the central figure in the priest Geoffrey of Monmouth's History of the Kings of Britain. Geoffrey died in 1154, and during the following generations many medieval writers were attracted to his portrait of a warrior-hero-king, and made use of it. My choice of episodes was determined by two objectives. I wanted them to throw light on what was happening to Arthur de Caldicot in his own life, and on the values underpinning it, and I wanted my readers to experience a full-bodied version and exploration of the King Arthur story.

What types of research helped you to create such a vivid picture of the Middle Ages?

Total immersion! I read and read and read; I listened to early medieval music; I went to museums and galleries and stared at artifacts and paintings; I talked to friends more expert than I in the medieval world; I traveled to places named in the novels (Ludlow in England, Venice in Italy, Zara in Croatia) and stripped away their modern clothing and soaked them up. I imagined.

You give many details of life in earlier times in these books, and yet the writing is so fresh, the voices so compelling. Could you tell us something about your writing style and the way you approached the series?

For each detail I include, I throw dozens away. So I guess the first trick is to pick the right details, the most revealing details. Then I think one must simply write quick, clean, bright prose. For me, this means rewriting and rewriting: almost never adding, almost always cutting. It also means listening to the music my language makes, and constantly tuning it. This is never more important than with direct speech. Each of us makes his/her own music. I think that my work as a poet and librettist (writing words for opera and music theater) have colored the way I approached the trilogy. The little short chapters, for instance, are like arias: moments of anticipation or reflection, rather than full of action. And they're written in quite intense prose. That's OK for a few paragraphs, but the reader would probably die of indigestion if I went on like that for page after page. I handwrite my books, incidentally, with my lovely Waterman pen. Black ink. A waiting page ....

What do the old legends mean to you, to all of us in the present day?

The Arthurian legends are not the product of one person or place or time. The very opposite, in fact. They're a great treasure hoard, a great quarry, like the Old Testament stories or the Greek or Norse myths. And within them they contain stories revolving around just about every aspect of human behaviour. Our idealism and generosity of spirit and laughter and energy and resourcefulness but also our greed and dishonesty and even cruelty.... All this is there in the Arthurian legends and in traditional tales as whole: and that's why they are just as startlingly alive and relevant now as they have always been. They show action and consequence. They are concerned with the utter joy and predicament of being human. They give us back ourselves.

The character of Merlin, present in the lives of both Arthurs, is a mysterious figure. What does he represent to you?

My Merlin gives Arthur de Caldicot his seeing stone, moves between worlds, and educates both Arthurs (as often as not by answering their questions with questions). He points out that the best way we can learn is to work out things for ourselves. In his person, the best of Christianity and Paganism combine; he is eclectic and tolerant. In a way, Merlin makes all this happen- the legends of King Arthur, and Arthur de Caldicot's exposure to them. He is a sort of magical impresario.

It's hard to imagine that we are finished with Arthur's story. Do you have any plans to write more about him and his life at Catmole?

I'm writing a novel about Gatty, the village girl who is Arthur de Caldicot's friend. I'm sending her on a great journey. A pilgrimage to Jerusalem. When she comes home, Arthur will be there, won't he, there and eager to hear her story. And then? Who knows!