20 September 1921: birth of Jack Kine, visual effects designer whose photograph is used on screen for the facist leader of the parallel Britain in Inferno (Third Doctor, 1970).
20 September 1925: birth of John Wiles, innovative producer who succeeded Verity Lambert but did not last long in 1965-66.
Also 20 September 1925: birth of Christopher Barry, who directed nine and a half stories from the first four Doctors between 1963 and 1980.
20 September 1969: birth of Mina Anwar who played Rani's mother Gita in the Sarah Jane Adventures. and also appeared as Goodthing in Smile (Twelfth Doctor, 2017).
20 September 1986: death of Dennis Spooner, script editor in 1965 and author of The Reign of Terror (First Doctor, 1964), The Romans (First Doctor, 1965), The Time Meddler (First Doctor, 1965), much of The Daleks' Master Plan (First Doctor, 1965-6) and the first episode of The Power of the Daleks (Second Doctor, 1966).
20 September 2000: death of Mary Ridge, who directed Terminus (Fifth Doctor, 1983)
ii) broadcast anniversaries
20 September 1975: broadcast of fourth episode of Terror of the Zygons. The Doctor foils the Zygons' attempt to attack London with the Loch Ness Monster, and Harry stays behind on Earth.
20 September 1980: broadcast of fourth episode of The Leisure Hive. Pangol attempts to create an army of dupicates of himself, but the Doctor and Romana regress him to infancy, and depart.
20 September 1986: broadcast of third episode of The Mysterious Planet (ToaTL #3). The Doctor and Peri continue being chased around the mysterious planet, now revealed to be Earth.
20 September 1989: broadcast of the third episode of Battlefield. The grand battle between UNIT and Mordred's forces, though this turns out to have been a diversion.
20 September 2015: broadcast of Time Heist. The Doctor and Clara find that they are robbing a maximum security bank, but why?