23 January 1921: as noted yesterday, birth of Kevin Stoney, who played Mavic Chen in The Daleks' Master Plan (1965-66), Tobias Vaughn in The Invasion (1968), and Tyrum in Revenge of the Cybermen (1975).
ii) broadcast anniversaries
23 January 1965: broadcast of "All Roads Lead to Rome", second episode of the story we now call The Romans. The Doctor and Vicki meet Nero, the Doctor pretending to be the murdered musician Petullian. Barbara is sold as a handmaiden to the Empress, Ian is shipwrecked.
23 January 1971: broadcast of fourth episode of Terror of the Autons. The Doctor persuades the Master that the Nestenes will go for him too, and together they repel the invasion. The Master escapes.
23 January 2008: broadcast of Sleeper (Torchwood), the one with homicidal aliens disguised as humans. (That doesn't help you remember which one it is? Really?)