“I am the world's most appalling martial artist. I am so bad. I've studied jujits…” — Nick Harkaway

I'm not shy, exactly, but I am private. I don't like to talk about myself. I had to learn - I was interviewed for print, radio and even TV.

There is not now, nor I suspect will there ever be, a le Carre novel with ninjas in it. Most serious novelists are wary of including ninjas in their writing. That's a shame, because many much-admired works of modern fiction could benefit from a few.

Suddenly, the idea of writing a book was like coming home. I didn't tell anyone except my wife, Clare. I just began.

My dad and I compete on the pool table; that's the most important competition of our lives. The fact that I'm writing and it works for me is one of the great joys for him. We talk about writing, and it's great.