Portrait: Yasmin Kerr

It is late on Friday afternoon and the traders of Portobello Market are just packing up for the day when Yasmin Kerr arrives to have her photograph taken. As she poses at the photographer's bequest among the emptying stalls the market is closing up around her. Kerr, the daughter of Simple Minds frontman Jim Kerr and Pretenders singer Chrissie Hynde is just getting started. In every sense of the word.

When we meet she is just days away from turning 18 and weeks away from making her TV debut in 40, a new Channel 4 drama series, in the illustrious company of Eddie Izzard, Joanne Whalley and Kerry Fox.

It is Kerr's first major role. Actually, it's her first role, period. She plays the mixed up 15-year-old daughter of a particularly messed up couple. Along the way, Bryan Elsley's script takes in nudity, adultery, copious drug-use, a frankly rather nasty spot of sado-masochism and a school reunion for fortysomethings. So, Yasmin, what was it about 40 that appealed to you exactly?

''When I went into the audition they said 'why do you like this?' and I said 'because I'd definitely want to watch it if it was on TV.' I'm a pervert like that.''

Next thing she knew, she was on set, stripping off to her undies in front of Izzard and the TV crew. ''I was pleased to get this job, so all the other stuff, the taking my top off stuff, it was a case of just getting on with it, have a few swigs of vodka and you're away.''

Apart from the odd Saturday acting class where everyone else was looking to get parts in the next Colgate ad, Kerr has had no drama school experience. Before getting the part, she had spent five months as a waitress and was considering going back to school until she was discovered by the agent mother of her friend Phoebe, herself a would-be film director.

''We'd write little sketches and make little films on her camcorder and people obviously thought 'hmm, that's okay' and started putting me up for stuff.''

Now Pippa Markham, Phoebe's mum, is Kerr's agent and the teenager is spending her time going to casting sessions.

So is she dreaming about a part in the next Martin Scorsese movie? ''No, not really because I think it's completely unrealistic. I think it's completely unrealistic that I'm even in 40. I went up for this Brad Pitt movie, Troy, and I just felt like this is stupid.'' The whole thing, she says, just seemed out of her league.

Kerr grew up in north London, around Kilburn and Maida Vale. She still lives in the area with Chrissie Hynde. She says she's inherited her father's sense of humour and his politics. From her mother, she got the irritability. ''It's all the bad things about my mum that people say I'm like.''

Rock 'n' roll parents are not, she has found, any more liberal than others. ''No, not really. I wish I could have great anecdotes like 'Oh yeah, I was shooting up with Slash in my kitchen.' But we were always in bed before 9pm, you know.''

She is constantly being asked about her parents. If truth be told, it can get a little tiresome? ''Oh, totally. But you know what? I'm not going to complain about it because it's always been like that.''

Certainly there was never any temptation to play the link down. ''When I told my dad I got the part he said 'Oh don't go and change your name or anything. Don't be afraid to be yourself,''' she says in a pretty decent imitation of her father's Glaswegian brogue. ''And I'm not. I'm not embarrassed by it. And I really like them so I don't mind talking about them.''

But for now, she has her own nascent career to chat about. She would like to do more acting, but if it doesn't work out something else will turn up. Frankly, she's not worried if 40 turns out to be her only moment in the sun.

''There's so much pressure on young people to be completely extraordinary and it's just unrealistic. Some people can be fulfilled marrying the milkman.''

For the moment, though, she is not planning to order in any more goldtops.

40, Channel Four, 10pm, April 8, 9 and 10.