The role you've been ascribed in childhood can twist or break apart or seem outgrown, especially when you have your own family and begin to see your own childhood from a different angle. You remember. You reassess. I think that was the kernel of the novel for me. This idea that you change but that your family, the people you were born into, might find that change hard to accept. You no longer fit the mold you've always been ascribed. When the adult children in the book converge back on their small family home there's a sense that they don't fit there anymore.

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.

Listen. The trees in this story are stirring, trembling, readjusting themselves. A breeze is coming in gusts off the sea, and it is almost as if the trees know, in their restlessness, in their head-tossing impatience, that something is about to happen.

While I was writing the book, one of my children was diagnosed with dyslexia. Dyslexia is a very tiny word for a wide-ranging neurological condition that affects different people in different ways. But I was reading an awful lot about it, to try and find ways of helping my child. I think a lot of fiction comes from this desire to confront unanswerable questions, and it's heartbreaking to see your child, a bright child, struggling so much with something that others are finding so easy. It's such an assault to the child's self-esteem and, as a mother, it's hard to watch.

What are you supposed to do with all the love you have for somebody if that person is no longer there? What happens to all that leftover love? Do you suppress it? Do you ignore it? Are you supposed to give it to someone else?

You learn so much with each book, but it's what you teach yourself by writing your own books and by reading good books written by other people - that's the key. You don't want to worry too much about other people's responses to your work, not during the writing and not after. You just need to read and write, and keep going.

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."