My favourite Friday treat is to drive out of the centre of Cambridge, where we live, and go for a swim at the health club I've just joined out in the countryside at Quy. It's a lovely pool, inside a converted barn. Usually it's just me and a couple of other swimmers there.

I was working as a secretary in Manchester and thought I would always do that. Then I got this letter offering me a two-year fellowship where I could write; they would pay me a salary and give me a flat to live in. It was heaven.

I usually go to the swimming pool if I want to swim.

Cambridge is heaven, I am convinced it is the nicest place in the world to live. As you walk round, most people look incredibly bright, as if they are probably off to win a Nobel prize.

I joined the swim team when I was 12, and I was the worst kid in the pool - I was put with a group of 7-year-olds.

The brilliant thing about swimming is that, while you're doing it, there's nothing else you could be getting on with, like the ironing or sorting out the children. My mind goes into free-float mode; some of the best ideas for plots come into my head while I'm ploughing up and down the pool.