"We met at the birthday party of a foreign correspondent friend of mine. I'd just had my first novel published and someone told me this woman was interested in writing so I very kindly told her how to write a synopsis, letters to editors and how to get a book going and she listened very politely and then left," he recalls.

"Someone then told me she had written numerous books that had been published in 20 different languages. I just wondered what she might have thought of this upstart."

The couple, who live in Beijing but have other homes in Chongqing (where Hong Ying is from) and in Italy, says they have different approaches to writing.

"She is a much more private writer. When I write something, I want the world to hear my brilliant prose. She keeps it very much inside herself," he says.

"We sometimes discuss our work. She did a wonderful job with the Chinese editions of my books, polishing the translations. The Chinese versions are probably much better than the English ones."

Williams says it took five years to write his first book, which runs to more than 800 pages, at weekends and during holidays.

"I never did it in company time. I used to say that I don't play golf at the weekends so I needed something else to do," he says.

Williams, who has published one other book, apart from the trilogy, set around the Spanish Civil War, The Book of the Alchemist, is now working on another novel.

"It is a sort of medieval detective story using some of the back story of the Spanish Civil War book. I was struggling with it but now it is going well," he says.

"I need to be alone and have quiet to write. It is not so much about having the time available but getting into the space where the story is in your mind."