John Hart (The Sea Devils)

Captain John Hart of the Royal Navy worked at the secret naval research centre, HMS Seaspite. Jane Blythe worked as his secretary.

The Third Doctor arrived at the base and Hart telephoned security when he saw him on the beach. He was brought to Hart where he explained he was from UNIT. After Jo Grant was able to clarify this he let them go.

Hart refused to have the Doctor taken to a sea fort station, describing it as "joyriding him around". After the Doctor and Jo were reported missing he telephoned for an air sea rescue helicopter. (TV: The Sea Devils)