'I just got off the plane from Paris. After this I'm getting on a plane to Tokyo. I've been doing interviews for you guys all day.' She swears at the crowd, holds up her middle finger and thrusts it at the swirl of bodies.

Pedro Winter, helmsman of Ed Banger records to which Uffie is signed, lurches onto the stage from one side. 'Anna,' he implores, taking her arm. She shakes him off with a toss of her head and chants, 'On strike! On strike! On strike!' in the monotone of a petulant child. 'How French,' drawls one partygoer, as he pushes his way out.

It would be easy to write Hartley off now, to call her a brat and judge her incarnation as Uffie as the cynically packaged electro-pop parcel that it might be. And that's probably what we'd have done, had we not met her earlier in the day and been disarmed. She is smart and openly self-conscious. She's polite enough and funny in a deadpan sort of way. But she's tired, and not just any old tired. The girl is exhausted to the bone.

When we meet Hartley before her show on August 6, she is limping through Diesel's headquarters in Central, directing a weak smile at no one in particular. She's clutching a take-away coffee from Starbucks, which she draws from distractedly. She is wearing grey jeans with a thick studded belt, a grey vest and a dark, cotton waistcoat. Her blonde hair is held back with a variety of hairpins. Stylists fuss. The entourage hovers. She disappears for a smoke in the stairwell. And eventually, Hartley settles into an armchair and fixes her wide, brown eyes on us.

The last four years of her life in Paris have been, it seems, a jading process wrapped in moments of glittering mania. A short marriage to graffiti artist Andr? Saraiva in 2008, the birth of their daughter, Henrietta, and the production of her album Sex Dreams and Denim Jeans have been packed in behind non-stop tours that have left Hartley little time to breathe.

'It's all gone really, really, really, really fast,' she marvels of her own phenomenon. 'It was a total shock. I haven't had a chance to step back and be like, 'Wow, this is actually happening'.'

Born in Miami to English and American parents, Hartley led an itinerant childhood. Her family moved to Hong Kong when she was five years old, settling in Discovery Bay, and stayed until she was nine. 'It sounds strange to everyone else,' she says of living here, 'but to me it was normal.'

Although she was too young to form many distinct memories of her time in the city, Hartley believes its cosmopolitan nature had a lasting influence on her outlook: 'Hong Kong is such a hub of the world. I think [growing up here] made me a lot more able to adapt to different cultures.'

After leaving Hong Kong, she shuttled between three cities in the United States and, by her mid-teens, had found herself in Paris. 'I consider myself from nowhere,' the 22-year-old claims in a tone thinly laced with defiance. 'I move around all the time, so I don't have a base.'

As a devout clubber in the French capital, Hartley met the rising DJ Feadz. He introduced her to Gaspard Aug? and Xavier de Rosnay of the Grammy-winning electro duo Justice. Feadz and Justice are signed to Ed Banger, which at the time had yet to reach the level of global acclaim it maintains today.

Winter's 12-year management of Daft Punk and the launch of Ed Banger in 2003 had, nonetheless, established the Frenchman as one of the most important producers on the electronic underground. Through the label, he fronted an anarchic post-electro movement that brought noise back to clubland.

It wasn't long before Hartley fell under his wing. 'I grew up around those guys,' she explains. 'When I was 17 turning 18 Feadz convinced me to write a song, and that was Pop the Glock.'

The single went viral through a contact at MySpace who put Uffie on the site's top artists roster in time for the song's launch in Europe in 2006. Pop the Glock became one of the most successful internet tracks of the millennium. 'Pedro heard it, and offered me a contract.' She shrugs, as though the achievement had nothing to do with her. 'So I went from school to the world.'

The music industry is a dark world, DJ Kodh explains later. An 18-year-old ing?nue plunged into its fray would be lucky to exit without scars. Hartley has seen things on tour she will not talk about, and calls the writing of Sex Dreams 'like therapy'. The rush of fame was bewildering. 'I got so much attention, I felt like it was undeserved,' she admits. 'I hadn't proved myself artistically.'

It was producer Mirwais (of Madonna's Music and American Life albums) who challenged Hartley to step up as an artist. We can hear the evolution on Sex Dreams, which was released in June after three years in creation. Uffie's early work is brash and reliant on the electronic wizardry of French electro producers such as Feadz and Mr Oizo. But the recent tracks move her into the more cohesive realm of pop, which she takes on with heart and something approaching irony. Her current single, ADD SUV, made with rapper Pharrell Williams, is a catchy foray into hip hop.

But critics warn that Uffie may have missed her chance to break into the mainstream, because it took four years and a string of delays to release Sex Dreams.

'I started four years ago. How do you magically make an album?' Hartley snorts, splaying her fingers at the ceiling in frustration. 'We were touring non-stop. And I think, from the day you start, you need a few years to find yourself as an artist. If I had released it two years ago, like I was supposed to, it would have been like the other EPs I'd released. I think it's important to go deeper and challenge myself.'

There is no mention of Hartley's surprise leap into motherhood. At a prompt, she allows a little: 'I think for any young working mum it's definitely hard. But it brings balance to your life. This industry is crazy hectic so to go home and have that normality is really nice.'

Hartley won't tie her work to one genre ('It's just music that inspires people to feel something, whether it's happiness or sadness'), and insists that Sex Dreams is more for her than her fans, 'a diary of [her] youth' composed over three years. She says of the album's title, 'I think sex is a very important part of adolescence and denim, to me, is the fabric of rebellion. So it kind of just summed up my life.'

Back at the Diesel party, a group of 20 or so people join Uffie on stage as she half-raps the first line of her track Difficult ('Don't worry if I write rhymes, I write cheques'). She punctuates 'cheques' with a bounce of her head and, for about 10 minutes, all is well. Then, she starts pushing kids off stage in a way that's less rock'n'roll, more 'you're p***ing me off'.

Finally, Hartley walks into the crowd and yells 'Hong Kong, we f***ing love you' before she turns, face falling, to be led away by her people.

Uffie on Uffie

Which living person do you most admire? Vivienne Westwood

Which talent would you most like to have? To fly

Who are your favourite writers? Michel Houellebecq and Bret Easton Ellis

Who is your favourite hero of fiction? Harry Potter

What do you dislike most? Fake friends