The big difference between Pratchett's eccentric fantasy worlds and, say, Tolkien's, is that - though equally dependent on trolls, witches and magic - Pratchett's are both instantly recognisable and funny. The inhabitants of Discworld worry about property values while the gods look down from a lofty place called Dunmanifestin. The children's books are the same: ripping escapist yarns full of contemporary references (computer games, parental marriage problems) and the kind of jokes and wordplay that flatter the reader. You want your offspring to read more? Make 'em laugh.
Terry Pratchett's books sell by the lorryload: four million copies of his Discworld novels in Britain alone, to say nothing of his children's fiction which this week (and not for the first time) gets him to the top of both the hardback and paperback bestseller lists. Only the likes of Catherine Cookson and Frederick Forsyth can compete. If you're thinking Pratchett's oeuvre must be pretty low-grade stuff, think again. Johnny and the Dead won him the Writers' Guild Best Children's Writer award last year, and librarians love him because he gets even reluctant young readers hooked on the book habit.