According to Bonnie Wright, there is one golden rule for survival on the Harry Potter set. In a banqueting scene, you must never be filmed actually eating,' she says very seriously.
Otherwise you'll have to keep on for the sake of continuity. The food gets cold and stale, and you start to feel really sick.' (Especially if the director is David Yates, notorious for his numerous retakes.) You have to make sure the spoon only goes as far as your lips.'
Bonnie has learned such tricks the hard way, having joined the cast to play Ginny Weasley, Ron's little sister, when she was a mere nine years old and had no acting experience whatsoever, barring roles in school plays.
Over the past nine years, she has seen her role expand from infant sidekick to leading lady. In the forthcoming film, Harry Potter and the Half-Blood Prince, she and Harry fall for one another, and their relationship proves more durable than his earlier ill-fated fling with Cho Chang.
In fact, as anyone who's read the final book will know (spoiler alert!), Ginny and Harry end up happily married with their own family. They've been discussing how they're going to do that,' she says gleefully. We might be aged with latex wrinkles…'
She'll certainly need them: in the flesh, she looks absurdly youthful, far younger than her 18 years. As she sidles into Shoreditch House, I half expect a kindly waiter to direct her to the crèche on the floor below.
Bonnie is small and willowy, dressed in jeans and unmade-up apart from a dab of mascara. Even the trademark auburn mane is a toned-down shade of ginger biscuit in real life.
They put highlights in it to bring out the red,' she explains. So although she's reached her majority, it somehow seems slightly wrong that she and the equally baby-faced Daniel Radcliffe have been hard at it putting the snog into Hogwarts.
The Half-Blood Prince is the first film in which their lips actually meet, although they've been gazing wistfully at each other for ages.
It was slightly embarrassing because on set everyone knew that it was The Day when we'd kiss,' she admits. It was definitely a case of “pass the mints”. But at the moment of the scene, everything just worked.
Ginny kind of initiates what happens between her and Harry. He doesn't really know what to do because she's his best friend's sister, so she takes the lead. It was very calm and romantic.'
It was a restrained clinch, she confirms: It would have been more embarrassing to do a full-on number.'
The relationship seems to have taken even Bonnie by surprise. As I was reading the sixth book, when their relationship starts, I was quite shocked,' she confesses.
Right from the start, Ginny was sort of Harry's little sister. But I think it's sweet how the books slowly build the relationship.'
Bonnie doesn't have a boyfriend in real life – I'm married to Harry Potter!' she jokes.
Interestingly, my Hogwarts mole reports on-set gossip that she was initially quite keen on Daniel Radcliffe but that by the time he got around to reciprocating the interest, she'd moved on.
But Bonnie denies that she ever had a soft spot for The Boy Who Lived – That would be really embarrassing.' What about his crush on her? I hadn't heard about that,' she says primly, refusing to be drawn.
Bonnie comes across as a pleasant, unstarry, level-headed girl. So it must be disorientating to find herself in receipt of hundreds and hundreds' of fan letters; to find websites dedicated to analysing her looks; and to be recognised across the globe.
I was on holiday with my family in a tiny, tiny village in Greece that had hardly any inhabitants and suddenly all these kids came running up,' she agrees. That's when you see how far the films' influence has spread. It can make you feel a bit weird.'
Her family background is creative but not at all showbiz. She lives around the corner from Shoreditch House with her parents, Sheila Teague and Gary Wright, who own and run London jewellery company Wright & Teague.
The family obsession has always been art rather than acting. We were always being taken round galleries on holiday.'
Bonnie's elder brother Lewis, now 21, started his sister's career. He'd read the first two Harry Potter books and really enjoyed them,' she explains. He said I reminded him of Ginny.'
Then they heard there were castings for the first Potter film all over the country. On a whim, Bonnie asked her mother if she could have a go. I didn't think she'd follow it up. But she got the casting director's number from the publishers and sent in some pictures of me.'
When Bonnie was asked to audition, she hastily read the first book.
The first audition, in [producer] David Heyman's office, was kind of strange, as I didn't have any lines really,' she confesses.
And I had no idea of getting the part since there were probably loads of more experienced kids who'd been acting since the age of two.'
Eventually, her parents were told that she'd landed the role.
We were in the car, going to our house on the south coast, and you know when you can tell that your parents have something to say to you? They were just silent for ages, as if they were about to announce they were getting a divorce. When they finally told me, I remember screaming out of the window all the way up the motorway. I was ecstatic.'
At the time, of course, none of the Wrights knew what they were letting themselves in for.
In the first film, I was only on set for three or four days,' she explains. It was a really interesting thing to do, but not drastic; nothing life-changing. I think if my parents had realised how big it would end up, they'd have worried about how I was going to balance filming with family life and school.
But I started at such a young age, I was able to adapt. We all grew up together doing the film. Living in London has helped a lot. I've been able to go home to my own bed and see my friends at the weekend.'
She had a tutor on set, and when she wasn't filming, attended King Alfred's School, an arty independent school in North London, popular with actors, directors and TV types.
It's much harder for people like Evanna [Lynch, the Irish actress who plays Luna Lovegood].'
When Bonnie first arrived on set, she was a complete rookie who didn't even know what Action!' meant, let alone which her best side was.
Fortunately, as well as having her mother as chaperone, she was also immediately welcomed into the bosom of her substitute family, the Weasleys.
The first day of filming, they introduced me to Julie Walters and said, “This is your mum.”'
She adores what she calls her parallel family', especially Rupert Grint who is lovely'. When we do scenes with all of us, it gets quite giggly,' she says.
You can really tell on screen when people feel a real connection.'
She has also relished the opportunity to work with some great contemporary British actors. They don't have to give you any tips,' she says, Just watching them, you pick things up.'
Aside from Walters and Mark Williams (who plays Mr Weasley), she gets on especially well with Dumbledore, aka Michael Gambon, who is, she says, not as saintly as he looks. He's always good fun on set, always laughing,' she says.
During the climactic scene in which (spoiler alert!) Dumbledore falls to his death from the school's astron-omy tower, she says he was giggling as he lay there.' Her favourite occupation is visiting the different departments, from costume to carpentry.
The level of detail is amazing,' she confides. If there's a book in a scene,
it will be fully printed, even if nobody's
going to open it.'
Bonnie ha also become good friends with Emma Watson, Katie Leung (who plays her love rival, Cho) and Evanna Lynch. When we all come back to do the next film, it's really nice, like going back to school after the summer break. Even the premieres are like a school reunion.'
The comparison is an apt one. Child stars are traditionally doomed, in popular opinion at any rate, to a future of drug abuse and missed opportunities.
But Hogwarts seems to have done spectacularly well with its alumni.
From Radcliffe and Watson down, graduates of the most exclusive institution in history seem to be emerging into adulthood astonishingly well-balanced and mature.
Warner Bros reputedly has a policy of shielding what they call the Potter children' from the limelight, and warning them about the pitfalls of fame.
The kids have remained natural because we have protected them,' claims one executive.
You'll never catch them snorting cocaine at Boujis and they've all managed to do well at school.
Bonnie is no exception. When we meet, she is in the midst of revising for her A levels, which she is sitting before starting work on The Deathly Hallows.
She's taking art, photography, design technology and English, and will start at London's University of the Arts in September to study film and television. I want to continue performing,' she explains. I have such a love for the job. It's been nice to find something that I enjoy and makes me tick.'
A couple of other roles have come her way; most notably, she played the young Agatha Christie in a 2004 TV film.
She's saved up her earnings, which must run into millions, and will fund herself through university. It would have been so stupid to spend it and go out all the time,' she says sagely.
Money goes much faster than you think. It's amazing that I can provide for myself and live comfortably while I decide what to do.' Eventually, she hopes to use it to fund her own films.
She accepts that at the age of 18, her greatest success may already be behind her. In terms of box office sales, nothing will ever be at this scale,' she says. But personally speaking, I definitely think there'll be something bigger for me.'
