Emma Watson: The girl with the magic touch

Emma Watson grew up on screen but as an adult, she's making her mark in the fashion world. Harriet Walker meets the new face of Lancôme

Emma Watson looks surprisingly grown-up, I think, when I meet her at the Savoy Hotel.

Reclining on a plush cream sofa with short, slicked hair and red lips, wearing a fitted black cocktail dress, she is every inch the sophisticated socialite. Poor Emma Watson, I then counter immediately, having constantly to prove to people like me that she isn't 11-years-old any more.

Her new role as the face of Lancôme's "Rouge in Love" lipstick range will go some way towards changing that view – shot by Mario Testino, the campaign captures her youthful vitality in a new and chic, gamine expression. It's rather more urbane and quite apart from the reputation for precociousness that the Harry Potter franchise – fairly or not – has foisted upon her.

"As I've got older, and since I cut all my hair off, I've felt a bit more liberated about trying different things out," she smiles, when I suggest she has successfully shaken off the fetters of having played a gawky teenage witch for a decade. "I think there's this idea that lipstick is something quite old or something you'd only wear at night. The nice thing about these is that they're really translucent, like a tinted lip balm, so you can wear them in a more casual way."

If she sounds like a professional, that's because she has been one for the majority of her 21 years. Picked from thousands to play Hermione Granger at the age of nine, after eight auditions for producer David Heyman, Watson is now – eight films later – rumoured to be worth £43m. She signed a contract with Lancôme in April to feature in the commercial for its Trésor Midnight Rose fragrance, and has been at Selfridges all day to promote the brand's latest launch of lipstick and nail varnish.

"Make-up is actually something I've always really loved," she continues. "The hair and make-up department on the Potter films were the people who saw me first thing in the morning and last thing at night, so that space was somewhere I felt at home. When we had spare time on set, I'd do their make-up and get them to teach me how to do stuff." Make-up artist on the films Amanda Knight remembers Watson making up extras for crowd scenes, too, but Watson has today left it to the professionals. "I haven't had my make-up done for two or three months," she says, as if expecting me to say, "No way!" I raise my eyebrows and she laughs. "I know! But it's really weird for me because I used to have it done every day. So it felt like a treat today."

She refers regularly to privileges and treats, to feeling lucky and counting her blessings, and she doesn't seem troubled or distracted by the host of opportunities available to her. She is studying English at Oxford, on a secondment from the American Ivy League campus Brown.

"It's just given me time, really," she says. "People use their time at university and at school, which I didn't have, to really think about and figure out what they want to do, and who they want to be. And it's been so nice not to be pushed around or pushed into doing things."

In fact, Watson has carefully peppered her career with choices that pertain very closely to her own interests, putting her name to a collection for eco-fashion range People Tree as well as partnering with designer Alberta Ferretti to work on a "Pure Threads" ethical line too. Her next film, The Perks of Being a Wallflower, will be released later this year. She paints and reads books. She has, she tells me guiltily, a university essay to hand in the next day, not yet finished.

"Doing the Potters was such a bubble," she says, "and then having to figure out how to function in the real world has been a challenge. But it's been the small successes for me: I know how to use a washing machine, I can cook. It's worth it to me not to feel disconnected from everything, feeling like I'm in touch with people who do other things than acting or being in the entertainment industry."

In a few hours, she will host the Lancôme pre-Baftas party, posing in a crimson lace Valentino dress for the world's cameras. But for the moment, she has her bare feet hooked up underneath her and is fiddling with her BlackBerry; she looks at the basil plant poking out of my shopping bag and wonders what I'm having for dinner. She is terribly normal – if elfishly beautiful – in her rendition of a well-brought-up young woman.

"I think humour has been a help," she says. "I have schoolfriends, a group of people around me, who have carried me through this whole experience and aren't fazed if they ask, 'Oh what are you doing tomorrow?' and I say, 'I'm going up to see Mario [Testino] in Notting Hill, he's shooting me for the new Lancôme campaign.' I don't know – it is mad, and some days I feel a bit mad, but it's the balance that keeps me sane. I don't fully live it, this side of my life."

Watson is sanguine about the attention she receives and is logical about it; she plans to travel more now that she has a more lax schedule, and talks about going to the post office, buying milk, getting the Tube, though I can't believe for a minute that she is actually able to do these things fuss-free. "Some days, for some reason, I can't go anywhere and I'm like, 'That was a mistake,' and other days no one will even notice me."

There was a time, though, towards the end of the Potter franchise, when Watson came of age and began appearing on front rows at shows such as Chanel and Burberry, in whose billboard campaigns she featured along with her younger brother in 2009. "I was fully game for 'Throw me in this, throw me in that,'" she admits, "but I'd like to develop my own sense of style, and dress for myself. The press destroyed me over this Rodarte dress I once wore – it was bright blue with chains on it." She laughs and shivers slightly. "I loved it. And I wore a leather Christopher Kane dress with embroidered flowers all over it. It wasn't that crazy, but at the time..."

She seems to have ridden out the post-Potter publicity admirably, though. "Fashion gave me a chance to feel like I was something outside of Potter," she explains, of her appearances front row at shows such as Chanel and Burberry. "I'm a multidimensional person and that's the freedom of fashion: that you're able to reinvent yourself through how you dress and how you cut your hair or whatever."

Her haircut was, of course, an international sensation, and turned into a global debate. Was it a good idea, did she regret it, why did she do it? Watson faced compliments and criticism in equal measure, staggeringly so. This was more than the average celeb 'do and more like a cultural event: Potter fans were horrified, while the fashion industry discreetly applauded the severing of Hermione's bookish locks.

"I had journalists asking me if this meant I was coming out, if I was a lesbian now." She rolls her eyes. "That haircut did make me realise how subjective everyone's opinion is. Some people were crazy for it and some people just thought I'd lost my shit. All I can do is follow my instincts, because I'll never please everyone."