Puberty

My ten-year-old can fluently recite lines from a sex chatline. 'Yes, I'm wearing my school uniform, silly!' she simpers, 'And I've finished my oral, although I did find it a bit of a mouthful at first.'
The unwitting culprit is my father who thought that St Trinians was all cardigan-clad mischief-making under the wholesome eye of Joyce Grenfell and who therefore bought a DVD of the 21st-century remake from Age UK. When I arrive, my daughter is raptly viewing schoolgirls in black-frilled scanties running a telephonic sideline from their dormitory.
I waver. My daughter thinks she is watching a clutch of teens having a makeover and my dismay baffles her. If I grabbed the remote and trashed the disc I'd have to explain the offense and rouse even greater zeal. If I let her continue she would revolutionise her classmate's games in the school playground. 'Mum, I'm ten!' she protests as I mutter my misgivings. So, troubled, I let her continue and  the schoolgirls turn their attention to illicit vodka distilling.
Childcare manuals guide parents painstakingly through weaning, through toddler tantrums and through the first shock of school. They are silent, though, on the dilemmas that confront mothers of pubescent girls. My daughter wants to spend her pocket money on stick-on finger nails and eye shadow. I disapprove. But, now she's ten, should I let her? How often should I make allowances for hormones when she answers me back? At what point do childish food fads become legitimate independent preferences? At what age should I respect her wish to wear micro shorts of ripped denim? When does pocket money become an allowance?
The onset of adolescence has crept up on me unawares. My firstborn has outstripped me. Through habit I have run her bath, washed her dishes, cleaned her room. I knew that I had to instruct her on female biology, but only belatedly has it occurred to me to show her which Hoover nozzles to insert when and how to fry chicken.
There are boundaries I still refuse to cross: high heels, 9pm bedtimes, a mobile phone. But in another year even these will become blurred and I shall watch baffled as my little girl sashays into a world my adolescent self never yearned for.
For now, though, she is enough of a child to want to play badminton over the clothes line. She turns off the television and unpeels her plastic nails. Relieved, I don my badminton wellies and seize a racquet. 'What's your sports star name going to be?' she asks. 'Mum the Magnificent, ' I reply. 'What's yours?' Angel Eyes was her last one. But that was before St Trinians. She reflects for a moment then hitches her skinny jeans. 'From now on,' she announces, 'I'm going to be Posh Totty!'
Have you steered a daughter through puberty? How did you cope? And if you haven't yet, are you ready?