The Stars of Narnia

Each of the seven children's chronicles is based on one of the seven planets that comprised the heavens in medieval astrology, says a scholar whose theory is examined in the programme.

The explanation comes after more than five decades of literary and theological debate over whether Lewis devised the fantasies with a pattern in mind or created characters and events at random.

It is put forward by Reverend Dr Michael Ward, in his book Planet Narnia: The Seven Heavens in the Imagination of CS Lewis.

Norman Stone, director and producer of The Narnia Code, to be screened on BBC2 at Easter, says the theory is the "best explanation yet" for the chimerical nature of the books.