An intriguing insight into the evolution from book to film of Oxford author Phillip Pullman's fantasy novel Northern Lights unfolded at the Oxford Literary Festival.

More than 600 people heard from Mr Pullman about his novel - part of his Dark Materials trilogy - and how it was translated into the Hollywood film The Golden Compass.

Sitting alongside the author was the film's producer Deborah Forte and visual effects supervisor Michael Fink.

The Golden Compass, adapted and directed by Chris Weitz, is the first of three films based on Mr Pullman's trilogy.

Due for release in December, the film stars Nicole Kidman as Mrs Coulter, Daniel Craig as Lord Asriel and Dakota Blue Richards who plays the central character Lyra Belacqua.

Lyra and her animal demon live half wild among the students of the fictitious Jordan College in Oxford.

Scenes in the film were made in the grounds of Exeter College, where Mr Pullman studied before rising to fame in the world of literature.

Mr Pullman told the audience in Oxford Town Hall on Saturday: "I did not expect the book would be so successful and that it would be made into a film.

"It was so unlike the previous books and I thought it would sell even less than the others.

"When I met the production staff, I received a warm welcome.

"Not only that, I was impressed by the fact that they had read the books and knew the stories."