The making of large imaginary worlds, whole kingdoms with their landscape, their peoples and their politics (usually medieval, these, with barons, and kings good and bad) is a recurrent form of story. Cart and Cwidder is just such a story. North and south are at loggerheads; vile tyranny crushes the south. Clennan, the travelling singer with his cart, journeys between the two. He and his children are just entertainers, busking in one town after another for their bread—or so the children think, but Clennan is not only what he seems.

A fantasy adventure, especially one that culminates in the gathering of armies, epic fashion, invites comparison with [J.R.R. Tolkien's] The Hobbit; but this is not another derivative book, for Diana Wynne Jones has a subject of her own to involve us in. Not the eternal war of good and evil, as in Tolkien, but the mysterious power of song is at the heart of her story. For one of the instruments in Clennan's cart is a huge old cwidder, that once belonged to one of the heroes of his songs, and if played with passion enough this instrument does strange things. The book tells us not only how Clennan's children escaped their enemies, and brought home the true heir to his kingdom, but also how Moril learnt about the power of the cwidder, and the use and abuse to which it could be put by such as he. This deeper strand, though handled with a light touch, gives subtlety and thoughtfulness to a story that is otherwise full of such sunny charm that only the villainous Tholian is hard to believe in.