‘It was pretty tough turning 18,’ she says. ‘I realised that overnight I’d become fair game. I had a party in town and the pavements were just knee-deep with photographers trying to get a shot of me looking drunk, which wasn’t going to happen. I don’t have to drink to have a good time. The sickest part was when one photographer lay down on the floor to get a shot up my skirt.

‘The night it was legal for them to do it, they did it. I woke up the next day and felt completely violated by it all. That’s not something I want in my life. I just kept thinking that if it had happened a day earlier people would have sued their backsides off.

‘I find this whole thing about being 18 and everyone expecting me to be this object… I find the whole concept of being ‘sexy’ embarrassing and confusing. If I do a photo-shoot people desperately want to change me – dye my hair blonder, pluck my eyebrows, give me a fringe. Then there’s the choice of clothes. I know everyone wants a picture of me in a mini-skirt. But that’s not me. I feel uncomfortable. I’d never go out in a mini-skirt. It’s nothing to do with protecting the Hermione image. I wouldn’t do that.

‘Personally, I don’t actually think it’s even that sexy. What’s sexy about saying, “I’m here with my boobs out and a short skirt… have a look at everything I’ve got”? My idea of sexy is that less is more. The less you reveal the more people can wonder.’

‘I’ve had the same group of friends since junior school and it has saved me. People I’ve dated have been friends of friends. I’d be unlikely to go out with anyone famous. I just wouldn’t.

‘I don’t consider myself to be a celebrity. I don’t fit that mould. I worry that people have expectations of me being someone I’m not. I’m just finding myself and trying to live as normally as possible and be as normal as possible.

'I’ve never seen a “good behaviour” clause (she refers to her reported Warner contract) – I honestly think that’s a myth – but I actually wouldn’t ever need one. It’s just not necessary. I’m not tempted by parties or drugs. I don’t actually like being drunk, particularly in public. But I do understand why people get sucked into a party lifestyle. I can see how it happens so I’d never criticise someone who gets into all that. It can get pretty tough. But you have choices in life. If I want to lead as private and as normal a life as possible I just can’t go there. So I don’t.’

She grins. ‘Daniel (Radcliffe), Rupert (Grint) and me have been incredibly protected doing the Harry Potter movies. There seems to be this feeling that all of us were bursting to break out of these images we had created but that’s never been the case. We all share the same view. None of us court celebrity, none of us want to be part of the game.’

‘It’s a strong relationship but it’s not sexual,’ she says. ‘It’s very complex. A touching of souls. She was a very young girl and he was this older, incredible man. I read the script two years ago and just knew this was the perfect film for me.’