Tertullian Medford was an Adjudicator Provost-General on the Scientifica colony.
He was the lover of the Chief Scientist, Whitfield. Medford was a secret member of Unitatus, and believed the Machine was a potential threat to Earth security. He made the Fifth Doctor and Patience send the fusion bomb laden Machine back to ancient Gallifrey. To prevent them from diverting the Machine, he shot Patience in the back of the head, destroying her brain and thus her ability to regenerate. Before he could kill the Doctor as well, the Seventh Doctor, Roz and Adric rescued him. (PROSE: Cold Fusion, AUDIO: Cold Fusion)