Not only is a film version of the fantasy series under way at the same time as a stage adaptation is put together at the National Theatre, but Pullman is to publish a new companion piece to the trilogy in October. Called Lyra's Oxford, it will re-introduce readers to his heroine, Lyra, and celebrate the intricate and detailed fictional landscape that Pullman has created for her.

'At the heart of it is a new short story called 'Lyra and the Birds', explained Pullman this weekend. 'It's set a couple of years after the end of The Amber Spyglass, and refers both back and forward - so it's a sort of bridge between the trilogy and a longer book coming later, to be called The Book of Dust.'

Sitting on an Oxford rooftop, Lyra is drawn into a mystery when she sees a figure flying towards her, pursued by a flock of starlings.

The publishers, David Fickling Books, plan to give the work the appearance of an artefact or 'bundle' that has accidentally slipped between two worlds. It will contain a cloth map of Lyra's version of Oxford, complete with the topography of the fictional Jordan College, squashed between St Michael's College and Gabriel College, and will feature Bodley's Library along with the imaginatively-enhanced area of Jericho, the Pitt Rivers, and the mysterious hornbeam trees.

Pullman, who lives in Oxford, was an undergraduate at Exeter College, Oxford, between 1965 and 1968 and has based Jordan College, Lyra's home, upon his memories of Exeter. 'The book will consist of much more than just the story,' he explained. 'We wanted to create an object that was both intriguing and beautiful, and - like the story - was both self-contained and full of references elsewhere. There will be a map of Lyra's Oxford, like ours but different, and various other bits and pieces; and it will be illustrated by John Lawrence, the great master of the woodcut.'

Fickling has asked designers Trickett and Webb to help produce the book, while Lawrence has already done preliminary work on the illustrations. 'Readers of the trilogy will immediately know where they are,' said Fickling. 'I asked Philip if he could do some bits and pieces around the idea of a map and this book grew out of it. He always told me he couldn't write short stories, but it isn't true. Lyra is there right from the beginning with her daemon Pantalaimon and there will even be a postcard from this parallel Oxford. It will all go on sale in October for £9.99.'