i) births and deaths
27 September 1911: Birth of John Harvey, who played Professor Brett in The War Machines (First Doctor, 1966) and Officia in The Macra Terror (Second Doctor, 1967)
27 September 1921: birth of Milton Subotsky, who produced and wrote Dr. Who and the Daleks (1965) and Daleks - Invasion Earth 2150 AD (1966), the two cinema films starring Peter Cushing as Doctor Who.
27 September 1939: birth of Garrick Hagon, who played revolutionary/evolutionary leader Ky in The Mutants (Third Doctor, 1972), and the undertaker A Town Called Mercy (Eleventh Doctor, 2012).
27 September 2000: death of Daphne Dare, who did costumes for most of the first four seasons of Old Who.
ii) broadcast anniversaries
27 September 1975: broadcast of first episode of Planet of Evil. The Doctor and Sarah land on Zeta Minor and are captured by the crew of a Morestran space ship, who have been mysteriously losing team members to an 'orrible invisible monster...
27 September 1980: broadcast of first episode of Meglos. The Doctor and Romana materialise in the Prion system, but are trapped in a chronic hysteresis loop while Meglos, an evil cactus, plans to take over the planet of Tigella with the help of the Gaztaks, some passing space pirates. The local priestess resembles a former companion.
27 September 1986: broadcast of fourth episode of The Mysterious Planet (ToaTL #4). It all goes bang, really.
27 September 1989: broadcast of fourth episode of Battlefield. Morgaine frees the Destroyer, but the Brigadier shoots it with silver bullets, and Morgaine surrenders to UNIT; the girls go out for a night on the town in Bessie.
27 September 2014: broadcast of The Caretaker. The Doctor takes a job at Clara's school, greatly disrupting her relationship with Danny Pink.