I'd heard of this book because Neill did the pictures, and while he certainly did a lot of work unrelated to Oz, this one is a fantasy story published by Reilly & Lee. It's the story of a boy named Peter who befriends Princess Marianne, a resident of the castle near his home. There's a mystical dimension to their friendship, as the beginning of the book discusses how they knew each other even before being born. It's very episodic, with each chapter being a new adventure. There's one where Peter is accompanied by a cat and another by a dog, with neither of these pets even mentioned in earlier or later chapters. Our hero meets with a dragon, a troll, giants, fairies, and talking animals, with a lot of transformations and backstories along the way, and often increasing his fortune through his cleverness. In some more surreal events, Marianne has to escape marriage with a peacock, the fairies turn the children's parents into kids themselves, and she and Peter try to find a way to stay young forever and end up visiting the nursery where they lived in a past life. Towards the end, Peter tries to court the Princess, and has to go on a few quests for her father. On one of these quests, he visits St. Brandon's Isle and Ultima Thule, and encounters the Old Man of the Sea. The color drawings are very recognizably Neill's work.