22 April 1942: birth of Denis Lill, who played Dr. Fendleman in Image of the Fendahl (1977) and Sir George Hutchinson in The Awakening (1984).
22 April 1984: birth of Michelle Ryan, who played Christina de Souza in Planet of the Dead (2009).
22 April 1989: death of Kenny McBain, who directed The Horns of Nimon (1979-80).
ii) broadcast anniversaries
22 April 1967: broadcast of third episode of The Faceless Ones. The Doctor convinces the Commandant to let him investigate the mysterious disappearances.
22 April 1972: broadcast of third episode of The Mutants. Jo, the doctor, Cotton and Stubbs are trapped in the caves by the Marshall, with gas closing in.
22 April 2006: broadcast of Tooth and Claw. The Doctor and Rose save Queen Victoria from werewolves; she founds the Torchwood Institute.
(Odd coincidence that Pauline Collins features in two episodes shown exactly 39 years apart.)