4. Diving Into Fish Tank

“All my films have started with an image,” says Arnold. “It’s usually quite a strong image and it seems to come from nowhere.

"I don’t understand the image at first or what it means, but I want to know more about it so I start exploring it, try and understand it and what it means."

She refuses to talk about what the image is that inspires her films, but she admits that the council estates of Essex (similar to ones she grew up on) are also part of the film's DNA.

"It's got really wild spaces. And even that block of flats, there's loads of people there. There's lots of kids. Lots of energy. I don't see it as a bad place. There's this clichéd idea that estates are awful. They're not.

"We're the fifth country in the world and yet there's more kids living in poverty. There are reasons why those kids go out and do what they do. We should be asking questions, not accusing or judging. They're kids. They get very bad press."

Before anyone starts thinking that she's drawing on life experience for the story of disaffected, under-parented, troubled teen Mia, think again. "My films aren't autobiographical. Those things have never directly happened to me. My mind goes places, I have an imagination."

The story that flowed focused on Mia, a headstrong, unhappy teen who must navigate her unsatisfying life with single mum Joanne and the new arrival in her life - her mother's boyfriend, Connor.

And why "Fish Tank"? "People want a title very quickly for the press packs but I need to get a feel for the film first. There’s lots of life in this little fish tank, in the small area shown in the film and Fish Tank is a good metaphor for it."

Arnold is specific about the loose way she writes her scripts: "I let the characters live and not question them or judge them and follow them around.

"I really think thinking is not a good thing to do when you're trying to write something. You shouldn't think. Thinking is bad."

But she certainly put some thought into who she wanted for her lead…

Next: Casting uknown leads