When I read Joan Aiken as a teenager there were only 4 books. I loved Wolves of Willoughby Chase, Blackhearts in Battersea was OK, and I loved Nightbirds on Nantucket. But then the Cuckoo Tree was more Dido and still no more Bonnie and Sylvia and I can't remember anything about it. And then I grew up and didn't know there were more of them. I will get hold of them and reconcile my teenage self to it being all about Dido forever.