Mr Campbell was the manager of UNIT's electronics supply shop in the 1970s.
Carol Bell had warned Liz Shaw that Campbell liked to flirt with the few female officers in UNIT HQ. Liz therefore felt uneasy when she went to find some components for the Third Doctor's electron microscope. (PROSE: The Scales of Injustice)
Jo Grant arranged with Campbell to deliver some parts to the Third Doctor's laboratory. Jo thought he was "a dolly Scotsman". (TV: Terror of the Autons)