7 April 1934: birth of Arthur Cox, who played Cully in The Dominators (Second Doctor, 1968) and Mr Henderson in The Eleventh Hour (Eleventh Doctor, 2010), one of the longest gaps between first and second appearances on the show.
7 Apruil 2017: death of Tim Pigott-Smith, who played Captain Harker in The Claws of Axos (Third Doctor, 1971) and Marco in The Masque of Mandragora (Fourth Doctor, 1976).
ii) broadcast anniversaries
7 April 1973: broadcast of first episode of Planet of the Daleks. Jo and the Doctor land on Spiridon and separately encounter a Thal expedition.
7 April 2007: broadcast of The Shakespeare Code. The Doctor and Martha, visiting 1599 London, foil a plot by the Carrionites to invade the Earth via Shakespeare's plays.