"He looked at me as though I was a victim of some sort of terrible arrested development," says Rennison, in a tone that seems to be constantly wavering around the edge of laughter. If that was indeed what he was thinking, Buerk wasn't far wrong.

"I admit to arrested development. I wallow in it," says the writer. "Most people who know me say there's not a lot of difference between me and the girls I write about..." You can only admire a 50-something who so fervently identifies with the dilemmas of those 40 years younger. But it must have a down side – like agony over nose/bra cup/bottom size, for a start.

Since Rennison burst out of stand-up comedy and onto the publishing scene 11 years ago with the refreshingly angst-ridden yet adorable voice of her teen heroine in Angus, Thongs and Full-Frontal Snogging, there have been nine more Georgia Nicolson books rejoicing in such fabulously juvenile titles as It's OK, I'm Wearing Really Big Knickers, Knocked Out By My Nunga-Nungas and Dancing In My Nuddy Pants.

Some parents blanche at the titles, but the charm of the stories is that Georgia N tries awfully hard to be über-cool and exude "sophisticosity" in front of the boys she fancies, but in many diary entries is likely to be worrying about her cat .

Each of the books has sold more than half a million in the UK, and in America (where Rennison is mobbed like a movie star) sales
are more likely to top a million
and top the New York Times bestseller list.

Georgia and her talk of snogging, "fabbity-fab-fab" friends, knickers and strops (as in bad temper) is an exotic creature to the teens of America, so much so that Rennison includes a glossary of Georgia Nicolson language in the back of each book.

The diaries are loosely based on those the writer herself kept as a teenager growing up on the Seacroft estate in Leeds. The colourful language was dreamed up not only to amuse herself but also as a kind of secret code to put prying parents off the scent. This need for privacy no doubt grew out of living in a three-bedroom house with her parents, sister, grandparents, an aunt and two uncles.

For all the talk of toning the lips ready for snogging Olympics, parents need not be too afraid of any ruinous moral decline encouraged by Rennison's creations. The action rarely gets beyond an exploratory clinch.

"I'm quite straight and prudish myself, and I don't think it's right for parents to discuss sex with their kids. It's far too embarrassing all round. An older teenager should do it."

Rennison, who lives in Brighton these days, says she doesn't accept the many invitations she gets to talk in schools ("I think it would spoil the mystique, really, if I had to sit in front of them and explain the characters and where I got them from...") but does enjoy her encounters with the mobs of teens (even boys) who flock to see her at signings.

"In America, two little girls came up and said 'We want to marry you'. They wanted to adopt me into their family, so they'd have constant access to the world they love.

"Many write me letters in a stream-of-consciousness style full of their worries and problems, talking as though they are Georgia Nicolson, and sometimes include little drawings. Others just ask 'what is 'hunky?'"

She says she was genuinely surprised by the success of the books. "I do wake up and think what a piece of luck that I was allowed to keep writing in this voice that was really me – uncompromised and unmoderated. Someone was clever enough to say to me 'if you write authentically about something you really know then that authenticity will shine and succeed.' It's certainly something you can't manufacture."

Someone was eventually going to make a film based on Rennison's books, and it happened last year, with director Gurinder Chadha directing Georgia Groome as the heroine of Angus, Thongs and Perfect Snogging.

Rennison is clearly still smarting at she recalls the experience. "I was not that happy with the film – although my bottom does make an appearance in it. I understood that writing a screenplay required different skills, and I wouldn't have minded other people rewriting my jokes if they'd done something funnier, but they didn't. And they put in awful words I never would have used, like 'minger'. It taught me that the film industry is only about money, not quality..."

But, in return for £30,000 for the film rights, she had signed away any right to whinge about the script or any other aspect of the production. At any rate, she's now adamant that there won't be another Georgia Nicolson film, so fans will just have to read and treasure the last of the her with the publication of the final volume of diaries, Are These My Basoomas I See Before Me?

Georgia now has a hot boyfriend on a scooter, a part in Romeo and Juliet, the usual feuds and makings up with the girls, a trying home life with a toddler sister and a dad in a Reliant Robin, and a "vair, vair" perplexing friendship with a bloke friend called Dave the Laugh. I am verboten to reveal how (and with whom) Georgia leaves her fans...

"People ask whether I'll feel devastated at saying goodbye to her and the answer is no, because I've lived with Georgia all my life and I can access her any time I want. What's more seriously worrying is how well I do with the next thing...

"It was time to let go of the Georgia books and do something different. I've become involved in the Scottish Wildcat Conservation Society (Georgia's cat Angus is part Scottish Wildcat), I quite fancy being in a play, and I'm starting what I hope will be a new series of books, set in a performing arts school that's... er, well ... not very good."

The 10 books have been kind to Louise Rennison. She's seen the world, goes to a luxury boot camp when she feels like it ("I haven't got a swimming pool, that would be a bit lonely..."), has been to 10 Downing Street ("Sarah looked a bit bored, so I gave her a signed copy of my book to cheer her up..."), and can afford to visit
her daughter Kim, who lives
in Singapore.

Rennison gave Kim up for adoption after getting pregnant as a teenager shortly after her family emigrated to New Zealand. Mother and daughter were reunited 16 years ago, but the writer says it's often daughter who puts the brakes on mother. "I think she thinks I'm mad. Having not watched her grow, I don't feel viscerally attached as other mothers do. We have a more friendly relationship.

"It's wonderful having her in my life, but I don't regret anything. I was a very young 17, and would have felt very stifled by a child. I knew we would meet again, though, and I sent letters to an agency to keep for her.." Despite two marriages, Rennison says she "never felt the urge to procreate".

"I've put my energies into
my art, if that doesn't sound
too corny. I admire women
with families who also manage
to write books or otherwise
create things. I couldn't have
done it."

sheena.hastings@ypn.co.uk

n Are These My Basoomas I See Before Me? by Louise Rennison is published by HarperCollins. £10.99. To order from the Yorkshire Post Bookshop call 0800 0153232 or go to www.yorkshirepostbookshop.
co.uk. Postage costs £2.75.