Your three novels are all set in late 19th-century Victorian England and have been praised for their historical accuracy. What motivated you to write about WWII?

Each of my previous novels grew out of the one before. I had a particular idea for Tipping the Velvet. I absolutely loved the period and I loved writing in that voice. But I needed to move on. I didn't want to go backwards in history, and the present doesn't especially interest me. I knew a little about the '40s, but there was enough I didn't know that made it appealing.

The chronology of events in The Night Watch is backwards from 1947 to 1941. Did you use this device to depict the urgency of life during the blitz years and the depression that followed, especially for women who had worked at what were considered men's jobs?

Yes, except I didn't see it straight away. The war itself is fairly familiar territory so I went there first. The moment I realized that what interested me is what had happened to the characters rather than what would happen, I knew I had my structure.

The heart of The Night Watch is a triangular lesbian love affair. Do you think that your novels have fostered a more understanding attitude toward lesbians?

I'd love to think that they've had some sort of influence. The fact that the books have been done on TV in Britain has given them a much wider impact than I'd ever imagined. I think that the English are now fairly tolerant. Things have changed enormously, even in the 20 years that I've been an adult.

As in all your novels, the sense of place is almost palpable.. Did you work with a map of London or do you do it all in your head?

Bits of both, actually. I've got a huge map of London on my wall. But I've lived in London for such a long time, I feel I know it very well. There are parts of London I particularly like and I always try to get them into my novels. It was a bit of a puzzle to get the characters to cross paths and fit together.

In your novels, characters are always lighting up cigarettes...

I've never smoked in my life, but when you look at '40s films, everybody smoked. There was something sexy about it. And in the Victorian period smoking was fairly outrageous, and that's what I wanted to convey.

Your novels are very popular in Britain. Do you have any special concerns about this one?

It was tricky for me writing about the war and its impact. So many people still alive have lived through it, and of course I'm hoping that I've got it right. I'll be very interested in how it's received—and in the States, too, of course.