I'm not in this book at all.

Rubbish. You're in everything you write.

I wrote most of the first draft of my debut, Before I Go to Sleep, in 2009, while attending a course at the Faber Academy. That course ended in the July, and there was a little party to celebrate, during which I met super-agent Clare Conville who told me she liked the sound of the book I was working on and would love to read it when it was done. Now, as I’m sure you can imagine, nothing spurs on a hungry debut novelist more than a top literary agent telling them she’s interested in their work, and I put my foot down on the accelerator and finished the book a month later.

This was the first draft, however (which I now call ‘Draft zero’, to remind myself it’s just the raw material and not intended for anyone’s eyes but my own) and so I put the book away for a few weeks and picked it up again in October/November. A rewrite later, and just after Christmas, I messaged Clare to tell her it was done and she invited me to her office to deliver the manuscript. As I handed it over she asked me a question which has stayed with me ever since. ‘Where are you in this book?‘

At the time it was an easy question to answer. I’d seen several aspiring novelists write thinly-veiled autobiography — and I’d even done it myself in one of my abandoned bottom-drawer novels that will never see the light of day — and realised that while tempting, it’s rarely a good idea. Everyone thinks their own story is fascinating, everyone is the hero of their own life. But often our lives do not translate well to fiction, and furthermore it can be harder to see where the problems lie in the work we’re doing if it’s a version of our own tale that we’re telling. And so, quite deliberately, I’d written a book about someone with whom I had nothing in common. She was a woman, for a start, and older than I was at the time, and in a very specific situation (living with catastrophic amnesia) which I was not.

And so, when Clare asked the question I replied confidently:

‘I’m not in this book at all,’ I said. I told her it was a work of pure fiction, nothing to do with me whatsoever.

‘Right,’ she said, knowingly. ‘Shall we go for cake?’

Fast forward…

A few years later, once the book was published and had found its success, I finally understood the reason for that knowing look. Clare knew something that, back then, I didn’t — we are always in the books we write, no matter how ‘fictional’ they are, no matter how far away from our real selves our characters may be. With the benefit of hindsight, I could see that in fact I was on every page of that book. I realised that, to me anyway, Before I Go to Sleep is on one level a book about someone approaching middle age who is struggling to work out who they are, who is taking stock of where they got to in life and comparing it to the ambitions they had as a younger person.

And — as someone who was then approaching 40 years of age, and felt stuck in a career they weren’t particularly enjoying and didn’t find all that fulfilling — that’s exactly where I was as I was writing it, though perhaps I wasn’t aware of it at the time, and certainly couldn’t see how it was infusing my fiction.

The truth is, on some level, all fiction is autobiographical. Even if it just boils down to the reason the author went with one story idea from their notebook and not another, or chose to write about this particular set of characters or that specific setting. There’s always a reason we make those decisions, and the reason is usually due to something deep inside ourselves that we’re grappling with.

So, should all writers ask themselves the question of where they are in the story?. And for every book? Yes. And also no. It’s my belief that it can help to know what part of yourself you’re bringing to the material. But there are many reasons why you might find it an impossible question to answer. You might be too close to see it right now, or working through something so deep that your conscious mind hasn’t even begun to process it now. You may never really understand why that particular story and those particular characters grabbed you and would’t let go.

And that’s fine. I wrote my book not really understanding that I was, on some level, writing about myself. I made the decisions I made, and it’s entirely possible that, if I had worked it out sooner, I might’ve steered too hard in the other direction, given up completely, or leaned too far into the autobiographical elements of the work.

With Before I Go to Sleep, on one level I thought I was ‘just’ writing a scary thriller about a woman with no memory, and it’s certainly possible to read the book as merely that. Or you can read it as a thriller with extras, some thoughts about identity, and loss. Some people have told me that to them it’s a book about love, and I can certainly see that too. But I believe that, certainly with the first draft, a writer doesn’t need to worry too much about what the theme of their book is. Those extra elements will creep in, almost whether you want them to or not, and you can amplify them in subsequent drafts, should you want to.

So, I suppose what I’m saying is go ahead. Ask yourself the question, by all means, but don’t worry too much if you don’t know the answer. It might take years for you to really understand where you are in the material, and it’s possible — even probable — that it’s only in the writing of the book that you can work it out. So just go for it, trust your instincts, and have fun. The rest comes later.