Teenage make-up is getting heavier and heavier. As an eyeliner addict, I have no right to comment on anyone slapping on fake tan and black mascara. (I blame Cheryl Cole. Eyelashes these days look like a crush of beetle legs.)

But when one of my daughter's friends from junior school said hello the other day, I had to blink hard before I recognised her. Her skin was bright orange, as if she'd been rolled in clay and cooked at high temperature in a kiln.

'They have to check their make-up between lessons,' says a friend of mine who teaches at a mixed secondary school.

Boys, by comparison, hardly look in the mirror.

'My 13-year-old was invited to go camping at half-term,' says a mum I've known for years, 'and she nearly said she couldn't go because it takes her half an hour in the bathroom every morning to put her face on.'

The problem with make-up is that everyone gets used to seeing you wearing it. So if you appear without blusher, or kohl, or foundation, you look naked. Get a girl hooked when she's 14, and she'll spend the rest of her life behind a mask.

'None of you needs make-up,' I said to my daughter the other day. 'You're all lovely as you are.'

'How old were you when you started wearing it?' says my daughter.

'We weren't allowed to wear it at school,' I say, prevaricating.

But we rolled up our skirts and painted ourselves with green eyeshadow the minute we were outside the school gates. And we probably would have gone orange, too, if only we'd known how to do it.