13 May 1938: birth of Milton Johns, who played Benik in The Enemy of the World (Second Doctor, 1967-68), Guy Crayford in The Android Invasion (Fourth Doctor, 1975), and Kelner in The Invasion of Time (Fourth Doctor, 1978)
13 May 1946: birth 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).
13 May 1949: birth of Zoe Wanamaker, who played Lady Cassandra in The End of the World (Ninth Doctor, 2005) and New Earth (Tenth Doctor, 2006).
13 May 1957: birth of Frances Barber, who played Madame Kovarian in Series 7 of New Who (2011).
ii) broadcast anniversaries
13 May 1967: sixth episode of The Faceless Ones; last appearance of Michael Craze as Ben and Anneke Wills as Polly. The Doctor brokers a deal between Earth and the Chameleons, and departs with Jamie.
13 May 1972: broadcast of sixth episode of The Mutants. Ky is transformed into a superbeing and kills the Marshal; Sondergaard stays on to help the other Solonians transform.
Neither The Faceless Ones nor The Mutants is my favourite story of the era, to put it mildly, but it’s an odd coincidence that the six episodes of each were broadcast on the same dates, five years apart.
13 May 2006: broadcast of Rise of the Cybermen. The Doctor, Rose and Mickey arrive in a parallel world where Rose's father is still alive and the Cybermen are coming.
13 May 2017: broadcast of Oxygen. The Doctor, Bill and Nardole investigate a strange space station, but are interrupted by walking dead in spacesuits... and the Doctor is blinded.