17 April 1924: birth of Clyde Pollitt, who played a Time Lord (the Chancellor) in The War Games (1969) and The Three Doctors (1973).
also 17 April 1924: birth of Kevin Lindsay, who played Linx in The Time Warrior (1973-74), Cho Je in Planet of the Spiders (1974), and Styre/The Marshal in The Sontaran Experiment (1975).
17 April 1941: birth of Brian Miller, who played Dugdale in Snakedance (1983) and Harry Stevens in The Mad Woman in the Attic (SJA, 2009); is also married to Elisabeth Sladen.
ii) broadcast anniversaries
17 April 1965: broadcast of "The Warlords", fourth episode of the story we now call The Crusade. Barbara escapes; Ian retrieves her, the Doctor and Vicki; and the time travellers depart.
17 April 1971: broadcast of second episode of Colony in Space. Jo talks to the colonists, and the Doctor talks to the IMC; and is threatened by the killer robot, again.