A city-nature novel.
Clay is an unusual novel in that, while it is set in London, the natural world plays a major part in the story. Indeed, Nature (capital N) could almost be seen as one of the novel's characters. Harrison is excellent at describing the changing seasons, and at how Nature just gets on with being in our cities—often without our noticing.
At the heart of this novel is the developing friendship between a troubled, nature-loving boy and a homesick Polish immigrant workman. The boy is also befriended by a comfortably middle-class girl, who spends much of her time with her grandmother. All of the characters are wonderfully developed, feeling like very real people, each with their own personalities and motivations.
A thoroughly enjoyable read.
Disclosure: I follow Melissa Harrison on Twitter, and consider her to be an online friend.