From the sanctuary of one's 20s and 30s, it is easy to regard our teenage years as a gauche wasteland of hormonal-fuelled angst best airbrushed from history. In author Louise Rennison's world, that brief hiatus between the demise of childhood and the onset of adulthood is instead hilarious and rather tender.
Her bestselling character Georgia Nicolson has become an institution among young female readers. First published in 1999, five million of her diary confessions and those of her more sensitive alter ego, Tallulah Casey, have been sold.
Rennison is now billed as the "Queen of Teen" by her publishers HarperCollins in a burgeoning market for adolescent fiction worth £42m a year. Pitched somewhere between Adrian Mole and Bridget Jones, her first book Angus, Thongs and Full Frontal Snogging has spawned a hit film and this week it will become the subject of a musical.
"If boys get any of it I'm really thrilled," admits Rennison, a former stand-up comic with a personal history that makes her evocation of girly teen life all the more intriguing.
Her books are based not on the vicissitudes of parenting experience but on pin-sharp memories of growing up amid an extended family on a council estate in Leeds in the 1960s – something she puts down to her Irish-Jewish storytelling heritage. And while many aspects of the books are autobiographical – the embarrassment of parents, disastrous episodes of eyebrow shaving, humiliatingly dressing up as an olive – others are not.
The writer became pregnant aged 16 when she was little older than her character, Georgia. Her baby was given over for adoption and the pair met for the first time only 15 years ago when Rennison was a successful performer and her daughter an adult. She recalls their first conversation. "My Mum phoned and said: 'I've got someone to talk to you'. So we had the first talk. It was quite kindly – nervous but kindly for both of us. She said she had always guessed that I was very young but she didn't know anything about me," she says. Today she is perhaps unsurprisingly guarded when talking about her daughter, although she says the two are very similar.
Like many working-class families at the time, Rennison's moved to New Zealand in search of a better life when she was 15. She hated it and after a few weeks of bitter protest was sent back to Yorkshire to live with her grandmother. After returning her goodbye gifts, she started going out with someone from a band and was dispatched back to the Antipodes, where she promptly got pregnant "out of sheer boredom".
The child was adopted by her ideal family – the father was an equine vet and the mother a ballerina – and Rennison eventually returned to Britain aged 20, alone.
In the years that followed, she hung around with rock bands, went back to college and became a successful comic. But she had been inspired by working on a youth project in Brixton, where she developed a liking for teenagers. So when the call came to write a teen diary from a publisher impressed with one of her "self-obsessed" magazine articles, she leapt at the chance.
"There is a prevailing attitude that you should all grow up but I'm not really reassured as to what that means. I think growing up would mean that you are incredibly tolerant and easygoing, liked everything, curious about the world because you weren't so egotistically driven. But actually I don't see a great deal of evidence of that [in adults]. They get frightened. They very often don't have more love, they have more fear. And that is a very nice aspect of teenagers – they just don't understand. They just say 'yeah'," she laughs.
Rennison believes teenage life remains fundamentally unchanged from when adolescent readers had to make do with the pages of Jackie for bespoke entertainment. And she studiously ignores the arrival of social media, mobile phones and the internet. "I don't pay any attention to that. I'm a real Luddite... The gadgets are different, the fashion is different, the speed is probably different but the emotional journey is pretty much the same," she says.
There is also a certain sympathy for the poor young male. "It's a cruel world they go back to. It's not like girls, who I know bicker and fall out and can be bitches ...With boys, it's like bloody Top Gear. There's no comfort for them, there's no checking with anyone, because they tend not to tell the truth to each other, really, especially emotional truth. God forbid sexual truth," she says.
And while there have been religious protests in the past against her books, for all their dreams of snogging and sniggering innuendo, it is an ultimately chaste and strangely old-fashioned world she creates. "Although Georgia is a pain and relentlessly thinks she is funny, she is not an unkind girl. There is a deliberate choice to be cheerful and that seems like a moral thing," she says.
Ultimately, she likes to make her young readers laugh. "I don't feel responsible. I like to cheer them on and I talk to them properly but I'm not a teacher. I don't think it's my job to teach in that way. Writing books is a different job."
Angus, Thongs and Even More Snogging, West Yorkshire Playhouse, Leeds, 11 February – 3 March.