Michael Ward is the author of Planet Narnia, which looks at the secret themes behind C.S. Lewis' Chronicles of Narnia series.

Planet Narnia was the subject of a TV documentary called The Narnia Code broadcast on BBC1, Easter 2009, and repeated on BBC4 a few weeks later.

Planet Narnia and The Narnia Code argue that Lewis secretly constructed the Chronicles of Narnia out of the imagery associated with the seven heavens of the medieval cosmos.

But is it really possible that Lewis could have invented and kept such a secret? Why would he have been so interested in medieval cosmology? What are the seven heavens? How come nobody has noticed this secret before? Does this hidden theme matter? How does it relate to Lewis's Christian beliefs?  Michael Ward provides answers...

'It's fun laying out all my books as a cathedral. Personally I'd make Miracles and the other "treatises" the cathedral school: my children's stories are the real side-chapels, each with its own little altar.'

C.S. Lewis