20 February 1913: birth of Rex Tucker, who is credited formally as director of The Gunfighters (1966) but also played an important role in the genesis of the show in 1963.
20 February 1954: birth of Anthony Stewart Head, who played Mr Finch/Brother Lazar in School Reunion (2006), Grayvorn in the 2002 Big Finish Excelis audio plays, and voiced characters in Death Comes to Time (2001-02) and The Inifnite Quest (2007) as well as doing voiceovers for most Doctor Who Confidentials since 2006. (Also Giles in Buffy, not that you needed reminding.)
ii) broadcast anniversaries
20 February 1965: broadcast of "The Zarbi", second episode of the story we now call The Web Planet. Barbara is captured first by the Menoptera and then by the Zarbi; the Zarbi get the Doctor and Ian too.
20 February 1971: broadcast of fourth episode of The Mind of Evil. The Master and his criminal helpers steal the Thunderbolt missile; meanwhile the alien inside the Keller machine is getting hungry...
20 February 2008: broadcast of Dead Man Walking (Torchwood), the one where Owen comes back to life.