But — and this really is the last part of the jigsaw that answers your questions about what happened to your father and why he left — when I was in hospital they discovered that my blood was rhesus negative D minus 7.1 can’t explain it now —you’ll learn all about blood at school — but it’s a very, very rare type; nearly everyone in the world has rhesus positive blood. Blood may all look the same but we all have different types and they kill each other if they’re mixed. But once they’ve done battle, once they’ve been in a fight, they learn enough about each other to have weapons already prepared if they ever meet again. Your blood is rhesus positive, so our bloods really don’t like each other but you survived because my blood hadn’t yet prepared its weapons. But while you were in my body my blood did build and prepare weapons forfuture use. If Td had another baby my blood would have killed it. Isn’t nature a wonderful thing? The reason I tell you this is because it helped me make up my mind not to have an abortion. If I didn’t have you I wasn’t going to have anyone else.

You were due on 4 November but didn’t see light of day until the eleventh. Always late — even then. What I said the other night is true: when I went to the hospital Dai Davies was at home in the basement flat. When, a week later, I went back home, he’d gone. He’d gone to the woman he loved more than me. It’s also true that I haven’t spoken to him since, nor has he ever explained to me why he left.

OK, so now you know the facts. I’m going to tell you what I think happened. I think your father wasn’t ready to marry.

I think he married someone who didn’t really exist, who maybe existed for an evening like a ghost — the beautiful woman at the graduation ball I think he wanted to be single, so he could have lots of girlfriends and other friends. I don’t think he wanted to be a father. I think he met someone he loved more than me. I don’t think he could tolerate the idea that you might not be the best, which had something to do with his vanity.

But, of course, you are the best. You’re Special.

I’m tired now, I’ve been writing for hours.

Read this and think about it for a while. I’ve tried to be fair, I’ve tried to be honest. One day I’ll teach you moral philosophy and then you can pick holes in everything I’ve written.

I love you.

This is the letter I’ve written to John. Of it I have two caveats. The first is that I’m not being entirely truthful: I did see Dai Davies again after he left. When I went back to Bristol from my parents’ house and begged him to come back. But I can’t tell John that now because I still can’t come to terms with having begged and been denied. The second is that I haven’t mentioned the hairgrip and I am not sure that I ever shall. It wasn’t a friend who told me of Dai’s affair, it wasn’t that I spotted them walking hand in hand, and it certainly wasn’t the case that Dai Davies told me what he was doing. I came home one night from work, seven months pregnant, and I found a hairgrip in our rumpled bed. One of those pins that look like an arcane punctuation point, or a musical notation. I pulled back the sheets and blankets and there it was on the pillow, black and stark, a fine exemplar of production-line engineering, with its ripples and in-built torque. It was functional. It was black, shiny, almost new. It was also not mine.