Jack was an orphan and spent much of his childhood in different care homes. He became involved in Charlie's organisation, but after a few years tired of the gangster life. However, he couldn't break free from Charlie's influence, partly because Charlie had a powerful weapon called the Lightning.
Jack and Charlie teamed up with the Fifth Doctor, Peri and Erimem. The Doctor planned robberies for Charlie to carry out. Unknown to Jack and Charlie, the Doctor had a specific goal in mind. He finally led them to a warehouse containing a cabinet. At this point, Jack and Charlie, as prearranged, turned on the Doctor. However, the Doctor returned the aliens in Charlie's weapon to the cabinet, their spaceship, and gave Jack several property deeds, freeing him from Charlie's control while Charlie was taken away to prison. (PROSE: The Gangster's Story)