The Several Lives of Orphan Jack by Sarah Ellis, 2003

When Jack, called Otherjack at the Opportunities School for Orphans and Foundlings, is apprenticed to a bookkeeper, he mistakenly believes he is going to be a keeper of books. When he discovers a bookkeeper is not exactly a keeper of books, he runs away. He finds himself in the town of Aberbog at a fair selling whims, ideas, notions. A delightful book. Highly recommended.