13 April 1924: birth of Christopher Tranchell, who played Roger Colbert in The Massacre (1966), Steven Jenkins in The Faceless Ones (1967), and Andred in The Invasion of Time (1978).
13 April 1951: birth of Peter Davison, who played the Fifth Doctor from 1982 to 1984, and subsequently. Happy 60th birthday, Peter!
13 April 1984: death of Richard Hurndall, who played the First Doctor in The Five Doctors (1983).
ii) broadcast anniversaries
13 April 1968: broadcast of fifth episode of Fury from the Deep. Weed and foam spread throughout the refinery.
13 April 1974: broadcast of fourth episode of The Monster of Peladon. The Pels unite against the Ice Warriors, but the Doctor is unable to prevent Ettis from firing the sonic lance.