The Warthog's express stood hissing at the platform nine and three-quarters of King Cross station as if straining at the leash, wanting to be set free, to thunder along the steel ribbons delivering its cargo of students to the academy of wizardly and witchcraft. Most of the students had boarded the train, ready for the Halloween term. Among those still milling around was Warthog's star pupil, Barry Potter and his friend R...