Is that retired CIA agent based on me?' 'No, Mum, she isn't.'

‘You know that mother character in The Hidden Girl who's described as a “joyless pit of misery”?' my mum asked recently. ‘Is that me?'

It isn't. And neither is she the frightening mother figure in The Playdate. Or the one who was hit by a deer on her way home from her daughter's wedding in Accidents Happen.

‘You know that mother character in The Hidden Girl who’s described as a “joyless pit of misery”?’ my mum asked recently. ‘Is that me?’

It isn’t. And neither is she the frightening mother figure in The Playdate. Or the one who was hit by a deer on her way home from her daughter’s wedding in Accidents Happen.

But it’s a question I’m often asked, probably because my psychological thrillers are set in domestic situations. They explore the real fears and anxieties that arise in our everyday relationships: can we trust another school mother with our child? Is there a hidden secret in my family background? Is my new partner telling the truth about who he is? Have I moved next door to a psychopath? (Honestly, I can go on like this for hours.)

It’s understandable, I think, when you’re a writer, that people look for clues in your domestic life as to how you write about relationships. At one party alone, I was asked by two different friends – one American, the other, tall and blond – if Suzy, the tall, blond American neighbour in The Playdate, was based on her. (Neither of them was.) I’ve also had a few winks from friends about the husbands in my novels. Believe me, if all seven or eight of them were based on my own husband, I’d be too busy in marriage counseling to write novels.

This wouldn’t happen as much, I suspect, if I wrote international spy novels. (‘Is that retired CIA agent who stops the nuclear weapon being stolen by warlords based on me?’ ‘No, Mum.’) The truth is that my characters are as imagined and invented as those of a writer in any other genre. I like to think of my sub-conscious humming away as I sleep, mixing elements from my own emotional landscape with the strange hair color of a girl I saw once in Copenhagen, the atmosphere of a ‘creepy old house’ film I watched as a child, and an anecdote a stranger told me on a plane. When I start writing, if I’m lucky, the outline of this new character will appear in my head, ready for my imagination to start work on developing them into a brand new fictional person.

There are times, of course, when a real-life story is so tantalizingly perfect, I’ll beg to use it. For The Playdate, a friend lent me a detail about her own nightmare neighbour, on the condition that I heavily disguised it. But I always, always ask. The last thing you want to do is upset those closest to you. After all, they’re the ones who bring you cake and give you hugs after Cathy on Amazon decides yours is the worst book she’s read this year.

But there are rare occasions, when something so intriguing and exceptional happens in real life, that it has to go straight in. In my new novel, The Hidden Girl, Will and Hannah move from London to a remote Suffolk village, only for Hannah to become stranded in an unexpected snowfall. Isolated and alone, she falls into the company of a local man called Dax, who starts to draw her into the secrets of this strange, cut-off village. The inspiration? A few years ago, a stranger on a ferry in Norway started a conversation with me that was so barbed and clever and twisting that within two minutes I was both in tears, and intrigued by the memory of him for days. That conversation was the seed for my character Dax. And with Dax, came the story of The Hidden Girl. Even if I tried to find that stranger again, I never could. He will never know.

And that’s all I’ll tell you. Because, if you’re like me, you don’t want to know too much about where characters come from. You want to read them and enjoy them; to find them believable and interesting. So, for instance, I could tell you the name of the very famous actress, whose photo is pinned above my writing desk, inspiring my new Scottish reporter character Grace in Book Four, but I won’t. I’ll leave it to you if you want to guess...