21 December 1915: birth of James Cairncross, who played Lemaitre in The Reign of Terror (1964) and Beta in The Krotons (1968-69).
21 December 1991: death of Colin Douglas who played Donald Bruce in The Enemy of the World (1967-68) and Reuben in Horror of Fang Rock (1977).
21 December 1998: death of Roger Avon, who played Saphadin in The Crusade (1965), Daxtar in The Daleks' Master Plan (1965) and Wells in the film Daleks - Invasion Earth 2150 AD (1966).
ii) broadcast and stage anniversaries
21 December 1963: broadcast of "The Dead Planet", first episode of the story we now call The Daleks. The Doctor, Ian, Susan and Barbara land on a strange world with a petrified forest and an abandoned city. But what is it that terrifies Barbara at the end?????
21 December 1965: first performance of the stage play Curse of the Daleks, by David Whitaker and Terry Nation.
21 December 1968: broadcast of eighth episode of The Invasion. Tobias Vaughn changes sides and helps defeat the Cybermen, though he too is killed.
21 December 1988: broadcast of second episode of The Greatest Show in the Galaxy. Ace is captured by the clowns; the Doctor is forced to perform for the circus.