I met a retired police detective. And he said to me that the interesting thing about heatwaves, from a police perspective, is that the number of people who just walk out of their lives when the weather gets unbearable is astronomic. He said the police prepare themselves for it - for a huge rise in the instances of missing persons. People choose to disappear when it's hot. It was fascinating.

All the time I was plowing through books on dyslexia, I found myself asking: what if, what if? What if you were a kid the 1950s with this condition, when there were no books on it, when there was no understanding of it. I remember kids in my class at school who just didn't seem to progress in their reading. There was no extra help. People just thought, "Oh, he or she isn't so bright, or they're obstinate."

I think all families have these secrets, and it's sometimes the strangest things that bring them out. That was part of my interest in the heatwave, in heat as a catalyst for uncovering truths. I was reading Alice in Wonderland to one of my kids recently, and I remembered that it starts on a really hot day. Alice falls asleep because of the heat; the whole story is predicated on falling into a heat-fueled dream.

As other authors have realized, heat can have a strange effect on us, can cause odd chemical reactions in the brain. Heat can bring out secrets; it can change people's personalities.

When my family moved from Ireland in the 70s, Britain was such a difficult place to be Irish. It was a decade of real social and economic upheaval in Britain. There were strikes, the three-day week, the oil crises, huge inflation, the winter of discontent and, what was it, four Prime Ministers? And relations between Britain and Ireland at that time were at an all-time low. I was born in the year of Bloody Sunday and of course the pub bombings happened in the mid-1970s.

My husband, William Sutcliffe, the writer, is my first reader and in many ways my most important. That initial reading of the manuscript is crucial and irreplaceable and you want them to approach it as someone in a bookshop might, not knowing much about it. So I've got into this pattern of not telling Will anything about the book I'm working on. He often knows nothing about the book I'm working on at all until I give him the whole manuscript and ask him to read it. The book I'm working on at the moment he knows nothing about. No one does.

I don't want to be influenced as to what I write in the next book, to hear those voices in my head when I'm writing. The idea of second-guessing your reader is dangerous, trying to please some notional reader looking over your shoulder, instead of just yourself.