As The Melkur, in "The Keeper of Traken", 1980.
(also features Roland Oliver)
While this is definitely the one and only Doctor Who appearance
that we can say with any certainty is actually Graham, the onscreen
credit goes to Geoffrey Beevers. Why? Because the Melkur is inhabited
by the Master (Beevers) — but the producers didn't want to give the game away.
See Doctor Who: The Television Companion
by David J Howe and Stephen James Walker, p 395.
contributed by arjuna