Written by Lucy Laing in the 1930s, the text is even more cringingly awful than the cover.
Here's a short extract:
(In this scene, Tom and Hugh find a "little black boy of about twelve years old" standing on his head. The author describes the boy as being "very black", with "thick, woolly hair, twinkling eyes and wide lips beneath which white teeth glistened beautifully")
"Are you our surprise?"
"No, young massa; I'se Sambo," he answered readily.
"Yes, but didn't our father bring you home as a surprise?" asked Hugh.
"Dunno 'bout dat, young massa. Cap'n bought dis chile back from ober de sea in big ship, and he say Sambo got to larn to be a servant."
Next time I start moaning about political correctness, I shall remember this book and shut up.