Despite its brevity, the serial boasted a few milestones. It was the first (and only) contribution by its writer and director. It offered the first outing of the Fifth Doctor's second costume, most notably differentiated by an obviously altered cricketing jumper. It was the first time in the show's history that the Doctor set his TARDIS on course to meet a member of a companion's family — in this case, Tegan's grandfather. It was also the final story designed by Barry Newbery, one of Verity Lambert's original designers.