An odd little book, this; it's a combination school story, family story and holiday story.
It opens with Our Heroine's father inheriting a small island in Cornwall, plus just about enough money to live on. So he throws up his hated office job in the Industrial North and removes the family to the island (which, conveniently, comes with a fully furnished house, two servants, and a couple of boats), where he plans to supplement his income by growing flowers and keeping hens.
The family quickly settles in, finds assorted relations living in the nearby port town, and learns lots of local tales and legends. The boys are sent to a nearby Grammar School; Our Heroine goes to the eponymous little green school, a tiny establishment run on rather informal lines where the girls are encouraged to find things out for themselves rather than learning by rote.
But the book is as much - more, really - about the family, the island, and the Cornish legends as about the school. It's somewhat episodic in structure, but the episodes are gently entertaining and overall it's a pleasant, soothing sort of book in which nothing much really happens but it's told very nicely. Not one of the author's best, but does well enough to while away a few hours.