It is a terrible thing to want something you cannot have. It takes you over. I couldn't think straight because of it. There was no one else, I realized, whom I could possibly tell.

In the course of writing a book I'll produce loads of pieces of paper to help the novel itself. Diagrams, charts, family trees. And at the end of each book I'll pack it all away. It takes me a while to do it - it's like a relationship that way; there's a period of letting - go, of grief, in a way - but then I box it up, label it, and put it in the attic.

The key thing in my becoming a writer was going on a Arvon Foundation residential writing course. I took with me a really messy twenty thousand words of something that later became After You'd Gone, my first novel. My tutors were Barbara Trapido and Elspeth Barker.

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.

We always planned to move back to the Republic but it never happened, I'm not sure why. My dad is one of those immigrants who never leaves the place he came from. He talks about Ireland all the time. If any Irishman wins at any sort of sport, he sees it as a personal achievement.

Despite being from Ireland, I've always avoided writing about it, for two reasons. For a very small country, Ireland has produced an astonishing number of literary geniuses, and at some level I probably never felt, having left as a toddler, that I had the right to try and add my voice. That's part of it. But I also didn't want to write something that was the equivalent of the Irish theme pub. You find them all over the world. The idea of producing a novel that might replicate that type of ersatz really set my teeth on edge.

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.