Thomas Piper is also the quotidian identity which Thomas Lynn and Polly initially invent for Tan Coul -- an ironmonger in Stow-on-the-Water who is unaware of his heroic nature until Hero arrives and tells him. He is quite strong from carrying around hardware supplies all day. Edna, his bullying sister, refuses to let him spend money on books; he had to give up tobacco in order to buy them, and then had to hide them in different covers, since Edna does not approve of pleasure reading. He resembles Don Quixote, since he is tall and thin, with an active, untrained imagination. His first heroic deed is driving a giant out of the local supermarket; he accomplishes this at Hero's urging, despite his own insistence that there are no such things as giants.
See also Fire and Hemlock (spoilers).