The problem with teenagers,” says the model Daisy Lowe, “is that they are so misunderstood.” This mantra has weathered tireless repetition over the decades since “teen age” was first identified, but, because Daisy is 19, stunning and slap bang in the thick of it, she is allowed to reinforce the point again.

“We aren’t any better or worse than the generations that went before us,” she continues. “Our problems always have and always will come down to one thing.” And that thing is? “Our bloody hormones. Give us a couple of years and we’ll all be fine.”

Daisy is feeling particularly hormonal at the moment.

So hormonal, in fact, that she has changed her shade of eyeliner from black to dark brown. The smudges don’t make such a mess, you see. There have been plenty of tears lately. “I am,” she notes, “absolutely heartbroken.”

It seems she only has her latest project to blame. Daisy and a jolly bunch of her hipster London friends were approached at the beginning of last year to take part in a documentary series for the BBC. Titled Class of 2008, it is perfect trinket TV: a transparent love letter to new metropolitan youth, accompanying a select crowd through the teens’ favoured playgrounds of Shoreditch, Camden and the occasional West End dive.

It is a valiant attempt to document the brilliant kids that you see on a daily (actually, mostly nightly) basis: messy, wonky, celebratory, empathetic, unapologetically ambitious. “People stare at me on the Tube,” says Kesh, 21, a fashion designer and one of Daisy’s crew. “I’m, like, I ain’t murdered anyone. Get over it. We look how we want to look.”

Kesh grew up in Crawley (“A cross between Hackney and Essex, without the black people”), was incubated under the UK garage noise of Oxide & Neutrino and So Solid Crew, and hung out with “boys in uniform Moschino and girls with their hair scraped back”. She says: “Things change so quickly now, it’s sick.”

Daisy’s other pals confirm the maxim. Portia Freeman, 19, a model who had a brief fling with Pete Doherty (“I’d rather not talk about that”), first dreamt of becoming a lawyer “just like Elle in Legally Blonde”. Daryl Fox-Huxley, 20, grew up on an estate in Bethnal Green and, on account of looking like a hot rock hero, was shot by Bruce Weber for an Abercrombie & Fitch campaign. Now he wants to be an actor. His life’s ambition is “trying not to be like anyone else”. Flash Louis, 18, is a beautiful lunatic (“I don’t take drugs because they give me panic attacks”) who used to present for MTV and hated it. Now he is a party promoter, DJ and “Facebook terrorist. I’m a lecherous internet pervert”. Will Cameron, 21, is in a band called Blondelle, has ginger hair, will mostly be wearing green this season, is an archetypal angsty poet and, in common with his generation, has the same relationship with the Smiths that his parents had with the Beatles.

Will is, or rather was, Daisy’s boyfriend.

Their recent split is the cause of her current heartbreak. “I love her more than I have ever loved anyone or anything,” he says, himself on the verge of tears.

Daisy says she fell in love with Will after staying up all night with him, just talking. He told her that his ambition was to be a great dad. “That was it,” she says. “He was unafraid to make a fool of himself. He did star jumps for me. We danced. I was madly in love.” I mention that I’ve spoken to Will. “Was he nice about me?” she says, wincing.

When asked what defines generations – attitudes to sex, love, drugs, music, fame, fashion, ambition, religion, politics – these kids come crashing back with a tirade of opinion. Politics mostly confuses them. “Politicians always talk about wanting to speak to young people,” Louis says. “It’s easy. Just f***ing do it.” Sex mostly excites them. “But wear a condom, please,” says Kesh, who feels embarrassed about the UK’s record on sexual health. Fame flummoxes them. “I just want to give Britney a big cuddle,” Portia says. Fashion is a game that anyone can play. “But please, be yourself,” says Kesh.

For the central trio – Daisy, Will and Louis – the television project was a no-brainer. “We all do different things, and this was a chance for us to hang out together, for a reason,” Daisy qualifies. “They are my best friends,” says Will. “I love Daisy and Will more than anyone,” says Louis.

For Daisy and Will, this could have turned into the new swinging London take on Katie & Peter: Unleashed. “It wasn’t intended to be a cheesy fly-on-the-wall, it’s observational documentary,” Daisy says. “They said they wouldn’t stitch us up,” Will says with youthful naivety.

One day, before filming started, Daisy was asked to move to New York for work. “Possibly for six months. Possibly longer,” says a love-struck Will now. “It was the hardest thing that’s ever happened to me.” In the course of filming, Will and Daisy broke up. Enter the brown eyeliner.

Whichever way you slice it, Class of 2008 is Daisy’s show. She is a thoroughly absorbing screen presence. Even when the show is less than perfect, she is. The couple are beautifully abandoned about the public interpretation of their relationship. They have none of the hard acquisition of the celebrities who sell their loves to OK! magazine, though they implicitly understand the game. Daisy and Will have graced the cover of iD magazine for nothing other than the chance to have their love captured, for a mercurial moment, by the ace photographer Terry Richardson.

For Daisy, the show is her step to the next level. She has a delightful manner, more grounded than you might expect from someone whose mother, Pearl, was in the low-level indie outfit Powder, and whose fondest childhood memory is, aged seven, being bought a necklace from Thorpe Park on a day out with Damon Albarn, “with the letter D on it. He told me it was the best letter, and that we shared it. I loved that”.

Perhaps because she was born into the grubby decadence of Primrose Hill, perhaps because she has been privy to more than most 19-year-olds, Daisy appears and sounds older than she is. She is a neat, cool, clever and accidental antidote to the idea that Britain is plagued by a rash of teen hoodies intent on global destruction from the top deck of a bus. “Drugs are so not just a young person’s thing,” she says. “They’re everybody’s thing. There are 40-and 50-year-olds who take shitloads of drugs. I’m not going to sit and preach, and I’m certainly not going to say that I don’t go out and get pissed. People can experiment as they like, but if they weren’t depressed before they started getting drunk all the time and taking loads of drugs, then they will be afterwards. I’ve seen it with my mum. She is so much happier without them.”

In New York, Daisy has been astonished at some American kids’ attitude to alcohol. “I’ve met young people who don’t drink. What do you do? Oh, you’re productive? Interesting.”

Daisy and her mother are inseparable. “We talk every day on the phone,” she says. “Without fail.” After she leaves LA, Daisy will be going to Brazil with her mum. “We’re going with Christian Aid to the favelas, to work with broken women who are drug addicts and prostitutes, and help them to learn to become seamstresses,” she says.

She explains that the charity needs “faces” to up the profile. Does it surprise her that, at 19, she is a “face” who can do this sort of thing? “To be fair, I’ve worked my arse off since I was 15,” she says. “My mum told me I had to get a Saturday job back then.” Back then! “I left school at 17 on the basis that I would work as hard as I would have if I was at school. And this is what it turned into.”

Daisy has weathered tabloid infamy once before, when Gavin Rossdale, Mr Gwen Stefani, was uncovered as her biological father. Daisy’s split with Will has caused similar ructions, particularly given recent sightings of Daisy with Amy Winehouse’s producer and persistent social presence Mark Ronson. She is sanguine about it: “I’ve been seeing Mark while I’ve been in America. He’s a lovely, down-to-earth guy. I like hanging out with him.”

She is still, however, in recovery from her first big love. “I’m a sucker for romance,” she says. “I still hold on to the fact that, one day, once I’ve got my career thing done, I can meet up with Will again. I’d love to have his children. I’ve been a crying wreck since we split up. I’ve never loved anybody as much as him.”

Daisy Lowe is the class of 2008, in every sense of the word.

Class of 2008 airs from Saturday on the BBC Switch zone on BBC2 for eight weeks

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