I think I'm in the same mood as ever, but in some ways more mature. I guess you could say that, at 65, when you've seen the world shape up as I have, there are only two things you can do: laugh or kill yourself.

You should have died when I killed you.

The good pupils are often brilliant, and they keep you on your toes and take you to the limits of your knowledge. The worst pupils provide a unique insight into the criminal mind.

Completing a book, it's a little like having a baby.... There's a feeling of relief and satisfaction when you get to the end. A feeling that you have brought your family, your characters, home. Then a sort of post-natal depression and then, very quickly, the horizon of a new book. The consolation that next time I will do it better.

But there is a big difference in working for the West and working for a totalitarian state.

The Secret Intelligence Service I knew occupied dusky suites of little rooms opposite St James's Park Tube station in London.

More particularly, having a largely German-oriented education has made me very responsive to 19th-century German literature.