Roly is a tidy, conscientious, intellectual counterpoint to the dreamy and messy Fimbles. In each episode, he tells them a story from his subterranean library, the best of which combine the crypto-communist subversion of Sesame Street with light-hearted, nonsensical plots beloved of earlier BBC shows like The Teletubbies and Bill and Ben. The stories are always preceded with a lullaby to Roly's love of books - "When you take a look, inside a book / Who knows what you might see / When you take a look, inside a book, it's fun as fun can be..."
Despite the heaving shelves, Roly always seems to read from the same book. This might have something to do with his absentmindedness. After The Fimbles ended, Roly got his own show, but fame didn't suit him. He stopped rolling, his stories became repetitive, and the show was cancelled after a year.