Sergeant Markham was a police officer in Georgian Oxfordshire. He was under the command of Sir Robert Muir. After Muir arrested the Fifth Doctor on suspicion of murder, Markham was ordered to convey him to the station. Before the arrest was accomplished, however, the Doctor exonerated himself by allowing Muir, Markham and Cummings to enter his TARDIS. (DW: Black Orchid)
