What were the main attributes that you wanted to remain in the film?

When I read the book, I saw the film in my head - which sounds like one of those typical clichéd Hollywood answers. I saw this film, I wanted to make this film, and I was obsessed. The three things I said to the studio and [producer] David Heyman when I first met them were: "I want it to be an all-British cast; shoot it all in England; and we have to remain as faithful to the book as time will allow." If you're going to do Shakespeare, you don't mess around with it, you don't touch it.

Given that millions of people already know the story, was it necessary to be secretive with the script?

It was an amazing conversation with the studio. They were going, "Maybe we should put the script in a library, and you have to go in and read it as if you were reading a library book." We had this ongoing argument, because we kept saying in the press: "We're being incredibly faithful to the book." My theory was, If you read the script, it's like reading a condensed version of the book. It's kind of a joke to me that there's this veil of secrecy to the script.

How would you describe your relationship with JK Rowling?

She was a collaborator, which I guess would be like a writer or a producer. She never held a stick over our heads and said: "You must do it this way." We would show her drawings of the Great Hall, we would get input from her on things like the Quidditch pitch, every aspect of the film. To me it was idiotic not to, it was stupid. I didn't feel hampered artistically, it was artistically liberating. As a director you want information, you try to get information. She's one of the best collaborators I've ever worked with.

Read part two of the interview.

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