Jack Chance was the leader of Sabalom Glitz's gang of robbers.
After the gang broke up, Jack became semi-legitimate, owning and running the Cafe Terrestrial on Vandor Prime. When the Sixth Doctor and Glitz tried to get him to join the reformed gang and do one last job on behalf of the Vandorian government, he refused. However, after the Cafe was raided in attempt to bring in the gang for questioning, Jack was forced to accept the Doctor and Glitz's offer. (PROSE: Mission: Impractical)