Saffy’s Angel is well-written young adult fluff. It has the bohemian arty family, an adoption, and a strict family to put the artists into context.
Fundamentally, Saffy discovers that she should inherit an angel, and most of the book revolves around her quest to try and recover it. But there are side plots, with sister Caddy’s torturous learning to drive with Michael Darling, the father who spends most of his time at his London studio and other adventures of the rest of the family.
There is lots of rich humour, with some children allowed to do what they want, and some much more constrained, and not a single one of them being set up to be taken seriously. It forms a nice light book, touching on serious topics. However I don’t feel any great need to read the other three in the series.