Benton first appeared in the Second Doctor serial "The Invasion" (1968), when he was just a corporal in UNIT. By the time of his next appearance in "The Ambassadors of Death" (1970) he had been promoted to Sergeant and quickly formed a close relationship with the Doctor, Captain Mike Yates and Brigadier Lethbridge-Stewart, the latter usually calling first for Benton when an order needed to be carried out. Benton's tour in UNIT also coincided with the tenure of the Third and Fourth Doctors as its Scientific Advisor, and his promotion to WO1 occurred immediately prior to "Robot" (1974–75).