I heard yesterday that a 14-year-old North London girl hanged herself in the night from a tree in her back garden. Her father discovered her in the morning and cut her down. There's an English expression that I don't normally use, but this information left me feeling gutted. Like a fish.

Poor child. Poor parents. Poor all of us.

As much as I write about adolescence, it's nearly impossible to experience the extremity of being fourteen in a middle-aged head. I'm 54, and know that sadness gives way to joy in about the same proportion that joy eventually segues back to sadness.  It's the human condition.

Or as my mother says, the wheel keeps turning.

I hug my own 14-year-old with tears in my eyes on a public bus and ask whether she's heard.

Yes, she says, a little crossly. And do you think just because we know people in the same school that it's sadder than any other child dying?

No, I say. Just a little bit closer to home.

We sit for a minute in silence.

Please promise me never to do that, I say to her, at the same time knowing that the contents of someone else's brain are always veiled, that teenagers are experts at keeping secrets, and that you never know what will happen next in your own life, much less your child's. It's a promise no one can make, or keep.

Knowing more about life than she does is what makes me cry when a stranger's child swings from a tree.