Abraham Derris-Cuthbertson was the founder of the DC Mining Company. He made a deal with the Travellers of Epajaenda. He offered them spacecraft so they could explore the stars, and in return he was allowed to mine their planet.
Three hundred years later, the Travellers returned to Epajaenda, waiting for Derris-Cuthbertson to return their planet to them. The Seventh Doctor assumed that he was long dead, but he returned to Epajaenda, took advantage of an anomaly on the planet to clean it up, and returned it to the Travellers. He was last seen by the Doctor being overwhelmed by the Rat Emperor. (PROSE: Last Rites)