Hexwood is one of my all-time favourite books. I find it helps one to understand it if you think of it as being in part a meditation on the art of filmmaking, with the action which will go to assemble the final story being filmed in sections which are chronologically out of sequence.

It also contains so many identifiable cross-references between Mordian and the figure of the Mabon in Celtic mythology that I suspect Diane of having deliberately used "Mabon and the Mysteries of Britain" and "Arthur and the Sovereignty of Britain" by Caitlin Matthews as source books.