Describe the origins of this book. What led you to the story of Henri II, Catherine de Medici, and Diane de Poitiers?

I have always been interested in my ancestors and once I learnt of my descent from both these women, I began to read about them and their times, their extraordinary lives, forming a royal triangle, a menage a trios, with the King at the court of Renaissance France. As a young woman, I wore only black and white, drove a black and white Mini, decorated my apartment entirely in black and white, and even acquired a black and white cat. Upon hearing this, my mother said, "It's time I told you about Diane de Poitiers."

How did you go about researching and writing this book? What sources did you use?

The books I found in libraries referred to the many letters written by the various ambassadors to the French court at the time. I began to search for the correspondence of the great names of the times that were either members of or had visited the French court. My husband accompanied me on my travels to the various locations where my principals lived, taking photographs to remind me, and helping with the on-site research. I hibernated in libraries in France and Italy, and was also fortunate in knowing the present owners of their houses who gave me total access. I also obtained much information from private archives through personal contacts. At Anet I found a small leather box, rather worn and shabby, that had contained Diane's trinkets - also her parasol. Diane would never let the sun darken that perfect white face.

On one trip to Chenonceau I was anxious to establish the veracity of a story that Diane would slip into the river naked almost daily. This seemed impossible; surely she would not undress by the riverside as the gardens were always full of people and the chateau is built high out of the water. The owners enabled me to take a small rowing boat under the arches of the bridge where I discovered a small metal stairway under the nearest arch leading to a trapdoor in a room above. So that was how she could enter the water unseen. There were letters at Anet, written in old French in Diane's distinctive strong hand, mostly about business. There is no trace of Diane at Chenonceau, nor at Chaumont, but at Anet, where her bones lie re-buried following the desecration of her tomb by the 1789 revolutionaries, she is everywhere present. The great libraries of France, primarily the Biblioteque Nationale, yield a wealth of information not only about Catherine and Diane but also about their times. The Serpent and the Moon is as much the story of Diane and Catherine's times as it is about their lives.

Once you have finished with your research, how do you approach the actual writing process?

Writing a book is a lonely business as, like many writers, I find it necessary to be left alone to do it, sometimes even to hibernate in some distant location. I allow no distractions - no TV, radio, or newspapers, and very little social communication. I need to enter the period and totally focus on it, to immerse myself and live the life of someone watching the people and the action within my story. Before I begin to write, I prepare my research notes into chapter 'piles', write an outline of the book, and decide on the chapter headings (though I must admit that sometime the book takes on its own direction and veers away from my outline.) It usually takes me a week to settle into a routine, where I then work for about ten to twelve hours a day. I read over the day's work after dinner, which means that I can move on to the next day without re-capping. I stick to a really strict routine for about three months and get the first draft, the "story" down on paper, and after that, I am more relaxed and take sections at a time to improve and re-do.

Why did you choose" The Serpent and the Moon" for the book's title?

The French Renaissance was an era of symbols, devices, coats of arms and family colors, since only the educated few could read. Grandees adopted symbols or personal devices to represent themselves. Diane primarily chose the crescent moon, as it is the primary symbol of her alter ego, Diana goddess of the Moon and the Chase. Catherine had a number of symbols, primarily the rainbow while her husband lived, but she had one device where a serpent, the sign of sagacity and also, to modern thinking, of duplicity and danger, made a circle biting its own tail. Both symbols seemed an apt way of describing the two women: Catherine - still, veiled and dangerous, Diane - brilliant, shining silver and risen high.

How did Catherine de Medici and Diane de Poitiers compare to each other? What do you consider the most significant difference between the two women?

They could not have been more different. There was a significant generation gap - Catherine could have been Diane's daughter. Diane was educated in the traditional way for a French lady from a great family, that is, in the house of an exceptional Princess of France. There she learnt the values, culture and courtly behavior necessary for a grand lady of the time. Although Catherine was born into the great house of Medici, she was an orphan and lived in constant fear of her life while growing up in Florence and Rome during very troubled political times. This fear for her future and lack of parental affection colored her behavior. Her life often depended on using her wits, her cunning and her ability to dissemble.

Catherine's personal motto was Hate and Wait. Could you explain why she chose this motto and how this affected her life?

"Hate and Wait" was said to have been her secret motto - that is to say, the court whispered it was so. Catherine had no standing at the French court. Her marriage was seen as a misalliance. Her father-in-law, François I, had placed her under the protection of her cousin Diane. Her husband loved only Diane, and Catherine, a woman alone in a foreign court and country, had no choice but to defer to her rival. Since Diane was her senior by eighteen years, it was more than likely she would pre-decease both Henri and Catherine. Therefore, silently Catherine could Hate and Wait to come into her rightful position by the King's side.

You write that during the time when the book is set, many people believed that the relationship between Henri and Diane was innocent, more similar to that of mother-son than lovers. What evidence is there to refute this belief? How would you describe Henri and Diane's relationship?

In the early days of the love affaire, many who saw them were not sure of the nature of the relationship between Diane and Henri due to their discretion, unusual in his father's libertine court. However, we have the evidence of their own letters and poems, and also of Catherine's letters, as well as the later, astute observances of some of the ambassadors. Theirs was a great love, the most famous love affair in French history, which lasted from Henri's childhood until his sudden death at the age of forty-two.

How would Henri II compare to the previous and subsequent kings of France? What were his strengths, and what were his weaknesses?

Henri was a quiet intellectual, not the flamboyant personality of his father, François I, the Renaissance king of France. He did not have his father's brilliance or his weaknesses for licentious living. He was said to have brought great stability to the kingdom through careful planning and resisted going to war when he could. His tragedy was that his opponent was his father's great enemy, the Emperor Charles V, the most canny and clever general and tactician of his time. The blot on Henri's otherwise excellent record is the continued persecution of the Protestants, but in this he was adhering to the values of his age and the heritage of his father. Henri II was succeeded by his three sons, François II, Charles X and Henri III, said to have been the three worst kings France ever had. None left issue and the throne passed to their brilliant cousin, the Bourbon king of Navarre and Henri IV of France.

How did the years spent in the Spanish prison permanently affect Henri's life?

Henri left France an ebullient child and returned four years later, sullen and resentful for the loss of his childhood. He blamed his father and never recovered from these dark moods or his antipathy towards François. Once his father died and he inherited the throne, it was said he looked as if a great weight had been lifted from his shoulders and he was actually seen to laugh.

What do you hope readers will take away from this book?

Several things: I hope they will be entranced with the story of a great romantic love set within the French Renaissance and enjoy reading about the cultural explosion of this exotic period. My aim in writing history has always been to interest people in the lives of the great men and women of the past and to appreciate the difference in the way of life lived in different centuries. Human nature does not change; just circumstances, and I believe we can learn so much from history, not just facts but also how to avoid the faults of the past. I see myself primarily as a storyteller, and my stories are true.