Jo Grant's uncle

 was the uncle of Jo Grant. Ostensibly Jo's mother's brother, he was a British secret agent, whose influence got Jo a job at UNIT. (DW: Terror of the Autons)

Jo once visited him when he was convalescing at Kenstone Hall, a recovery home for injured spies. While at the facility, she discovered that its patients were undergoing inexplicable healing and that its director had been replaced by the Master. (ST: The Touch of the Nurazh)