George Trenchard

George Trenchard was a human who was in charge of the prison on Fortress Island where was incarcerated.

Shortly after the Master arrived, he persuaded Trenchard (either through hypnotism or coercion) that "enemy agents" were working against him and the country. These "enemy agents" were also responsible for ships recently sunk in the area. Trenchard willingly helped the Master, going so far as to distract John Hart with talk of golf, while the Master stole various pieces of equipment.

Following the Master revealing his contact with the Sea Devils and a subsequent Sea Devil attack, he was killed after he shot a Sea Devil. (TV: The Sea Devils)