Grogan was one of the Edwardian sailors abducted from Earth by the Eternals to crew the Shadow. He was in the crew room when the Fifth Doctor and Turlough came aboard and was introduced to them by Jackson. When the crew received the summon for rum rations, Grogan made a hurried exit, telling Turlough he'd see him later.
Behind the scenes Edit
Pat Gorman is visible playing a crewmember aboard the Buccaneer in part four but it seems unlikely this was Grogan.