Peter Dickinson is the critic's joy, as well as the child's. Other writers, including the best, settle into a uniform excellence which is wholly to be admired but which scarcely lends itself to individual appreciation.

Mr Dickinson keeps us guessing. Will the next be about a society without machines, or a school of Loch Ness monsters, or the second sight, or the Byzantine Empire? Probably not, for he has had his say on these matters. The Blue Hawk seems to be about Pharaonic Egypt…. A little reflection suggests that this is too facile a view. The sacred river Tan whose waters keep the land fertile may seem like the Nile, but she flows south. Other details are equally disconcerting, and they give rise to more fundamental doubts. Are we in the past? The kingdom operates according to rituals whose rigidity suggests a civilization moving towards decay. It is...