I've now read the trilogy to Celyn and all three books are very good. Books 2 and 3 don't quite reach the highs of Howl's Moving Castle for me, but they're great stories to read to an 11 year old (I should note here that Celyn is severely disabled and can't read for herself). 
 The book was written 18 years after book 2, 22 years after book 1, and 3 years before the author's death. Despite that the feel of the thing is quite in keeping with the earlier instalments. 
 Once again we start with a new person and a new part of the world, with Sophie and Howl worked in tangentially about half way through the book. 
 Our protagonist is a young lady called Charmain who is roped into looking after her great aunt's great uncle's house while he's off being treated for some illness. The great uncle is a wizard, the house has ... many ways. 
 Much of the first half of the story concerns figuring out how to navigate and use the wizard's house. Charmain plunders the spell books and is joined by a boy sent to apprentice to the wizard. The plot, however, concerns the king of High Norland and his troubles, both financial and with his rather unpleasant heir. Sophie and Howl are brought in to help - their story entwines Charmain's and fun ensues. 
 It's a good and imaginative tale with moments of humour. I'm pleased to report that it doesn't repeat the formula of the first two books wherein a whole bunch of people/things turn out to be completely different people/things in the magical equivalent of pulling off the masks at the end of a Scooby Doo episode. 
 The only big surprise for me was that a baddie whose crimes seemed relatively mild is killed out of hand by our heroes toward the end. That didn't quite fit the mood music. Apart from that - a fun installment and a trilogy definitely worth buying for your 8 to 12 year olds. 
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