For me, a big part of writing psychological thrillers is choosing crimes committed for motives which would only apply to a particular person in a particular situation; a unique, one-off motive that is born out of someone's particular range of psychological afflictions.
Agatha Christie never wrote books that just started with a dead body, and a 'Let's find out who the murderer is', which is kind of mysterious but not that mysterious. She always started with, 'How can this thing be happening; isn't it strange?'
Only Agatha Christie can write like Agatha Christie.
Try as I might, Agatha Christie is unique. The actual writing style can't be exactly the same, so instead of trying to replicate it exactly, the way I got around it was by inventing a new narrator.
Nobody has ever written as many enjoyable, fun-to-read crime novels as Agatha Christie. It's all about the storytelling and the pleasure of the reader. She doesn't want to be deep or highbrow.
When I set out to write crime fiction, I didn't think to myself, 'I'm going to model myself on Agatha Christie' or 'I am going to be a crime writer in the Christie tradition'.
I am trying to write novels for properly clever people, but I also want them to be proper novels that also stick in a person's mind and have an atmosphere about them.
I am a fellow commoner at Lucy Cavendish College. My husband used to be a lecturer at Leeds University, and we lived in Yorkshire for 11 years. When he gave up his job, we realised we could live wherever we liked.
No highbrow literary type would ever say 'Moby Dick' is good but it's just about a whale, or a Jane Austen would be important if she wasn't just writing about romantic relationships.
Some writers, I'm told, look for their characters' surnames in telephone directories. I don't - it seems too obvious. Or too deliberate: if you go looking for names, you're bound to find them, of course, but I've always had a superstitious hunch that the names you find by accident are always going to be better and more satisfying somehow.
I never write about CIA conspiracies or the FBI or mafia or anything like that because I just don't understand that world. But I think I do understand individual human harmfulness.
Agatha Christie's writing is incredibly skillful because her books are incredibly intellectually puzzling and challenging.
I'm snobby about books that aren't crime fiction: if I start reading a literary novel and there's no mystery emerging in the first few pages, I'm like, 'Gah, this obviously isn't a proper book. Why would I want to carry on reading it?'
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.
There are very few well-adjusted people in my books. But I do think that's normal. Because everyone does have their issues and hang-ups.