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?

I have two sisters, and I think siblings are always going to be irresistible for novelists. They have been throughout time and they'll continue to be.

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.

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.

She wanted to say, no. She wanted to say, I have a son, there is a child, this cannot happen. Because you know that no one will ever love them like you do. You know that no one will look after them like you do. You know that it's an impossibility, it's unthinkable that you could be taken away, that you will have to leave them behind.

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.