Nothing very significant today, is there?

Oh, hang on…

i) broadcast and production anniversaries

23 November 1963: broadcast of "An Unearthly Child", first episode of the story we now cal An Unearthly Child, and the first ever episode of Doctor Who. Teachers Ian and Barbara follow their mysterious pupil home to a police box, which contains the time and space ship – the TARDIS – of the enigmatic Doctor. It transports them – but to where?

23 November 1968: broadcast of fourth episode of The Invasion. The Doctor and UNIT rescue Isobel and Zoe; and Jamie and the Dioctor witness a Cyberman emerging from its cocoon.

23 November 1983: first broadcast of The Five Doctors, in the USA. (British audiences see it two days later.) The First, Second, Third and Fifth Doctors are united on Gallifrey to play the Game of Rassilon.

23 November 1987: broadcast of first episode of Dragonfire, introducing Ace. The Doctor and Mel land on Iceworld where they encounter their old friend Sabalon Glitz, and a stroppy waitress.

23 November 1988: broadcast of first episode of Silver Nemesis. The Doctor and Ace go back and forth between Windsor Castle in 1988 and 1638, dealing with the Nemesis meteor and Lady Peinforte's status; then the Cybermen arrive.

23 November 1989: Silvester McCoy records the voiceover at the end of episode three of Survival, the very last words of Old Who.

23 November 2009: release of third episode of Dreamland.

23 November 2013: broadcast of The Day of the Doctor. The Tenth and Eleventh Doctors get together with the War Doctor to deal with the Zygons, Gallifrey is saved, and who's that at the end?

also 23 November 2013: release of The Five(ish) Doctors Reboot, which I would have loved to bits anyway, even without the crucially important fact that I myself am briefly visible in it about 8 minutes in.

ii) births and deaths

23 November 1914: birth of Roger Avon, who played Saphadin in The Crusade (First Doctor, 1965), Daxtar in The Daleks' Master Plan (First Doctor, 1965) and Wells in Daleks – Invasion Earth 2150 AD (Cushing movie, 1966)

23 November 1916: birth of Michael Gough, who played the Toymaker in The Celestial Toymaker (First Doctor, 1966) and Hedin in Arc of Infinity (Fifth Doctor, 1983). He was also married to actress Anneke Wills.

23 November 1963: birth of Joe Ahearne, who directed Dalek, Father's Day, Boom Town and Bad Wolf/The Parting of the Ways (all 2005).

23 November 1966: birth of Michelle Gomez, who played Missy in 2014-17 vs the Twelfth Doctor.

23 November 1990: death of Mostyn Evans, who played Dai Evans in The Green Death (1973) and the masked High Priest in Death to the Daleks (1974).

23 November 2003: death of Bill Strutton, writer of The Web Planet (1965) and the novelisation Doctor Who and the Zarbi.

23 November 2010: death, two days after her 73rd birthday, of Ingrid Pitt, who played Galleia in The Time Monster (Third Doctor, 1972) and Solow in Warriors of the Deep (Fifth Doctor, 1984) and co-wrote The Macros (originally submitted in the mid-80s, made by Big Finish as a Sixth Doctor story in 2010).

iii) dates specified in canon

23 November 1638: The Doctor launches the Nemesis statue into space. (Silver Nemesis, 1988)

23 November 1863: death of Victoria Waterfield's mother (according to Marc Platt's 1996 novel Downtime).

23 November 1963: setting of the K9 story The Cambridge Spy. (For my money, the worst episode of the entire show.)

23 November 1997: Re-coronation of Elizabeth II, attended by the Fourth Doctor, Romana and K9 in Lance Parkin's 1997 novel The Dying Days.