So what does the title mean?

Andrea Arnold: Yeah, I started off by explaining the title and now I've decided that's not a good thing. I'm going to stop explaining it. I think it can mean a lot of things and I think that's nice for people to think about. If I tell you what I think, that just makes it definite. And that spoils having some fun with thinking about why is it called Fish Tank. I think it's better you try to work it out. Sometimes if I dot the Is and cross the Ts, it spoils it. It's on the internet anyway!

How did you get the idea for Fish Tank?

AA: I always start with an image. I'm not telling you what it was! No, because again, it gives the film away. Even though everyone will be writing about exactly what happens on the internet and it's no mystery, I still have this idea of protecting what happens. Because I personally love to see films not knowing very much about them. When you see it, it's like a flower opening up. I deliberately never read about films before I see them.

What does Katie Jarvis think about all the acclaim she's getting?

AA: She has no idea how much she's been talked about. Her ears must be burning! I rang her during Cannes and said, "Katie, you've got to get on the internet. Get on the internet!" She hasn't got a computer where she is. And I was like, "Go somewhere and get on the internet!"

Fish Tank

Is it true that you found randomly her at a train station?

AA: Yeah, she was having a row with her boyfriend. He was on one platform and she was on the other. She was yelling at him. I wasn't there, it was actually the casting assistant called Lucy, who was really fantastic. She approached Katie and Katie didn't believe it was for a film. She thought Lucy was incredibly suspicious! And she's absolutely right to be suspicious! I'd be suspicious. But she came along, we did a local little audition with some girls we'd found in Tillbury. We just got her to do a little bit of improvisation. She could just be totally herself. Her family's not the same as Mia's in the film, but more her character and her energy and her anger. She's got the ability to quite angry. That was more the thing that was right for the part.

How did you know she could handle the really harsh scenes?

AA: I didn't know. It was a big risk in way, because I really didn't know if she would be able to do it. She could obviously be herself in a little bit of improvisation. But we have a script. And every day we have a certain amount of things to do. A story to tell. Cameras. Sounds. Things she has to learn very quickly. And I didn't know if she'd be able to do it. But I love leaping in and not knowing if it's going to work. It was a big risk. I thought, Hmm. It might not happen...

What about the sex scene?

AA: Yeah. She's 17 so... I spoke to her parents and they know that it's not real. You're only pretending. Obviously you try to make things look as real as possible. But in amongst all that, doing those things is hilarious, often. I'm sure she was nervous. But even people who've done it before get nervous so that's not surprising. We didn't make a big deal of it. We kept it very brief.

Fish Tank

Were you anything like Katie's character when you were a teenager?

AA: I don't think so... I did grow up on a housing estate. And I was a teenager, obviously! But I was never like Mia. I see a lot of those kids around and I know what it's like to be a teenager. I guess I'm projecting some other things on to her. To make her slightly different to what I know. So it's partly imagination, partly things I know.

How did you make all the dialogue so realistic?

AA: I just picked people who live there. They say things in the way they say things. Katie comes from that area, so she just scripted it into her own words. We kept Michael with his Irish accent, because he's a little bit of an outsider anyway. Kierston Wareing actually was born in that area too. Rebecca Griffiths lives down the road.

Do you think some audiences won't understand the slang?

AA: It's interesting doing the French translation. Because we're not only translating English, we're translating Essex English. So for example, one of kids says, "Oh, her mum's butters." Butters is slang for butt-ugly. Butt-ugly means arse-ugly. Trying to work that out in the French translation was very interesting... Trying to keep the language as colourful!