i) births and deaths

20 May 1926: birth of John Lucarotti, writer of the stories we now call Marco Polo (First Doctor, 1964), The Aztecs (First Doctor, 1964) and The Massacre (First Doctor, 1966)

20 May 1961: birth of Owen Teale, who played security guard Maldak in Vengeance on Varos (Sixth Doctor, 1985) and cannibal leader Evan Sherman in CountrycideTorchwood, 2006).

20 May 1966: death of Mervyn Pinfield, who was Associate Producer for Doctor Who from An Unearthly Child (First Doctor, 1963) to The Romans (First Doctor, 1965) and also directed The Sensorites (First Doctor, 1964), Planet of Giants (First Doctor, 1964) and The Space Museum (First Doctor, 1965).

20 May 1977: death of Lennie Mayne, who directed The Curse of Peladon (Third Doctor, 1972), The Three Doctors (Third Doctor and guests, 1972-73), The Monster of Peladon (Third Doctor, 1974) and The Hand of Fear (Fourth Doctor, 1976)

20 May 1982: birth of Jessica Raine, who played Emma Grayling in Hide (Eleventh Doctor, 2013) and Verity Lambert in An Adventure in Space and Time (docudrama, 2013).

20 May 1993: death of William Emms, author of TV story Galaxy 4 (First Doctor, 1965) and the widely and justly forgotten Sixth Doctor game book, Mission to Venus (1986).

20 May 1996: death of Jon Pertwee, who played the Third Doctor from 1970 to 1974, with occasional returns to the role.

ii) broadcast anniversaries

20 May 1967: broadcast of first episode of The Evil of the Daleks. The Tardis is stolen, and when the Doctor and Jamie pursue it, they find an antique shop with added Dalek.

20 May 1972: broadcast of first episode of The Time Monster. The Newton Institute near Cambridge is in fact run by the Master, who summons Kronos.

20 May 2006: broadcast of The Age of Steel. The Doctor and friends manage to infiltrate Cybus industries and destroy the Cybermen.

20 May 2017: broadcast of Extremis. The Pope asks the Twelfth Doctor to investigate a mysterious book called the Veritas.

20 May 2020: webcast of Listen, a poem by Stephen Moffatt tying in with the epuisode of the same name.

also 20 May 2020: webcast of Fear is a Superpower, last words from Danny Pink.