Standing on the edge of the dance floor, I peered enviously at the girls bopping to Beyonce and Girls Aloud, feeling a pang of jealousy at their stylish outfits. They were wearing skimpy little dresses I'd seen in shops but couldn't afford, and towering heels that I'd never be able to walk in.
The strange thing was, though, these girls were only 12 – and I was a 21-year-old woman. I was a nanny at the time, helping out at a party. I was shocked by how sophisticated, and super-sexualised, these kids' (and they were kids) outfits were.
Now in my mid-twenties, my own childhood wasn't that long ago. Of course, there were moments during my own schooldays that echoed this – like friends performing a raunchy dance to Sisqo's Thong Song aged 14 – but things were more conservative.
Today, while children's natural sexual development might not have changed, the world around them has. Miley Cyrus's now infamous 'twerking' performance at the recent VMA Awards caused a media frenzy, and her latest music video – in which she can be seen suggestively licking a sledgehammer and swinging naked on a giant wrecking ball – has also met with shock and criticism.
It's not that sexually explicit imagery hasn't always been part of popular culture; it's more about the fact that Cyrus – who shot to fame as fictional schoolgirl pop star Hannah Montana – is adored by pre-teen girls the world over.
For a few years now, shops have stocked thongs, push-up bras and adult-like high heels for girls as young as seven, and parents can purchase stationery for them featuring the Playboy logo. Sexually-themed adverts aimed at young girls seem to be everywhere – like the Skechers trainers ad, featuring Christina Aguilera dressed as a sexy schoolgirl, a pencil provocatively placed in her mouth.
In 2010, psychologist Dr Linda Papadopoulos carried out a review which reported that, while sexualised images have always appeared in the mass media, there's been an unprecedented rise in recent times.
It's a subject which worries Melissa Benn, a mother-of-two and author of What Shall We Tell Our Daughters: The Pleasures And Pressures Of Growing Up Female. "The sexualisation of girls is starting much younger," she says, adding that when girls are young, they're less aware of how the world views them, than we are when we get a bit older.
"That's a very important part of their development; it's a time when they are free to have a range of interests."
So why have these changes come about? Benn believes that, commercially, young girls are a new market which has emerged due to parents' increased responsiveness to their needs, and also because of the rise in working parents whose guilt makes them more likely to buy their kids presents.
Another big factor is the internet. Research by the London School of Economics found that a third of nine to 10 year olds go online every day, and 93% of nine to 16-year-olds use the web at least weekly. Often, they'll be doing this unsupervised, and though they may not be purposefully looking for sexual content, they could encounter it anyway – a YouGov survey found that a quarter of young people have received unsolicited pornographic junk mail or instant messages.
Recent reports of children sharing pornographic images on their mobiles at school are extremely alarming.
An American Psychological Association report stated that sexualisation and objectification can reduce body confidence, leading to feelings of shame, anxiety and self disgust. It also found that sexualisation's been linked to three of the most common mental health problems for females – eating disorders, low self-esteem and depression.
Is it any surprise? When you're bombarded with images of unrealistically perfect women, even a grown adult can feel inadequate.
Bryony Kimmings, a live artist, felt so strongly about the lack of non-sexualised role models for young girls that she created one herself – with the help of her nine-year-old niece, Taylor.
The result was a fictional character – Catherine Bennett (www.catherinebennett.so) – a palaeontologist and pop star who "loves tuna pasta, reading, writing songs about polar bears, doing Taekwondo and hanging out with friends" and, vitally, isn't pouting at cameras dressed in next to nothing.
"I chatted with school kids and realised how different they are to how I was. Growing up, I loved Prince; it was all about celebrating uniqueness, not pure sex appeal," explains Kimmings.
Melissa Benn says parents have a role to play too: "We, as parents and carers, can do a lot to instill confidence in our daughters."
She thinks how sex education's dealt with in schools should be addressed, too, and Diane Abbott's fighting for a purge on "sexualised imagery" in public spaces, while David Cameron has spoken about making the internet safer for children. Meanwhile, Mumsnet's Let Girls Be Girls campaign is asking retailers to stop marketing products that increase the premature sexualisation of young girls.
These are all, potentially, positive steps that could reverse this uncomfortable trend.
And I, for one, am backing them all the way.