Hindsight is the historian's necessary vice.

In my 20s I was in constant pain from undiagnosed endometriosis. With no prospect of a cure, I decided I needed a career - writing - that could accommodate being ill.

You think you're writing one historical novel and it turns into three, and I'm quite used to a short story turning into a novel - that's happened through my whole career.

Write a book you'd like to read. If you wouldn't read it, why would anybody else? Don't write for a perceived audience or market. It may well have vanished by the time your book's ready.

Like every writer, I'm drawn by unlikely juxtapositions, precisely-dated and once-only collisions between people from different worlds.

The writer I adore is Ivy Compton-Burnett.I couldn't get more than a few pages in when I first read her. In many ways, she is very clumsy and her plots are rubbish. But we don't read her for that. There are pages and pages of dialogue. What it requires is real effort and attention.

I didn't cry much after I was 35, but staggered stony-faced into middle age, a handkerchief still in my bag just in case.