I still have a stammer. I hate it; I loathe and despise it. But it's always there, and I have lots of ways to conceal it. I can conceal it now but I'm not good on the telephone. I get my husband to make dentist appointments. And I hate live radio. Hate it. I really try to avoid it at all costs. But it's always there. Stammerers become skilled at sentence construction and synonyms: we have to be. Faced with a problem word, we need to have instant access to eight others we could use instead - ones we could say without stumbling. I think my stammer is a huge part of my being a writer.

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 you'll know yourself, there are these moments when you're writing a book when one remark or moment will pull everything together and you'll think, "That's it. I've got what I need."

I think it was Rose Macaulay who said, "A house unkept cannot be so distressing as a life unlived."

When I worked at The Independent newspaper, I had colleagues who would laugh and say that whenever they picked up the phone to my dad and heard his accent, they thought they were about to hear a five-minute warning to get out the building. People in Britain have always thought it acceptable to make racist remarks about the Irish. The prejudice underlying that supposed joke was everywhere.