I finally tracked down a copy, and ds2 is transfixed.
He is normally extremely suspicious of any fiction, and doesn't go for stories at all - either to listen to or to read himself. I read him the first couple of chapters, and he was hugging himself with excitement, squealing, and laughing out loud. When I said I didn't have time to read any more he grabbed the book and was last seen disappearing upstairs.
So I guess it's a hit then! Thank you!
It's very well-written and a delight to read aloud too.