31 December

31 December was the final day of December when many Earth-based cultures celebrated New Year's Eve.

Holidays and observances
As the last day of December, 31 December was the date of New Year's Eve celebrations for many Earth-based cultures. It was not a well-known holiday by the year 4000, as Sara Kingdom did not recognise it. (TV: The Daleks' Master Plan)

Early years
In 1879, Queen Victoria issued the Torchwood Charter and founded the Torchwood Institute. (TV: Children of Earth: Day One; AUDIO: New Girl)

In 1899, the Torchwood One agent Gerald Kneale assisted Torchwood Three with the Centurian Incident and its clean-up in Cardiff. (COMIC: Rift War! Part Six: Circles)

In 1926, the Marylebone Cricket Club (MCC) played All India in the 2nd Unofficial Test match of the scene in Calcutta, British India. The MCC won the match by four wickets. The Fifth Doctor considered it to be one of the best cricket matches of all time. (AUDIO: The Emerald Tiger)

In 1930, the Eighth Doctor finally brought Charley Pollard to the Raffles Hotel in Singapore, but an old enemy of the Doctor soon forced them to leave for a whirlwind tour of history. (AUDIO: Seasons of Fear)

In 1965, chasing the Daleks, the First Doctor briefly materialised his TARDIS in Trafalgar Square during the New Year's Eve celebrations. (TV: The Daleks' Master Plan)

According to a calendar on the Snowcap base, 31 December 1986 was a Wednesday. (TV: The Tenth Planet) On that day, Ben and Polly reunited long after their travels with the Second Doctor had ended and they reflected on their time with him. (PROSE: Mondas Passing)

In 1993, Tko-Ma tried to escape his dimensional prison. He was stopped by the Sixth Doctor. (PROSE: Instruments of Darkness)

1999
1999 was an eventful year for 31 December.

The Sixth Doctor and Melanie Bush saved the Earth from being taken over by Saraquazel, a being from the after-universe, and his servant Ashley Chapel. (PROSE: Millennial Rites)

A younger version of the Seventh Doctor and an older version of Mel gate-crashed the New Year's Eve party being thrown by Alisha Hammerson, the Auton head of Hammerson Plastic PLC, in London. They foiled her plan to replace her guests with Auton replicas so the Earth could be dominated and absorbed by severing her link to the Nestene Consciousness. (COMIC: Plastic Millenium)

Inside the Walker General Hospital morgue, after having his regenerative ability delayed by anaesthetic, the Seventh Doctor regenerated into his eighth incarnation, forced his way out, and discovered his memories were gone too. The Doctor tried to convince Grace he was the same man she attended the previous day, and recruited her to help him with his bout of amnesia, eventually regaining his memories. Meanwhile, Chang Lee, having pocketed the Doctor's TARDIS key, began raiding it. The Master found Chang Lee in the TARDIS and manipulated him to open the Eye of Harmony. Opening the Eye destabilised Earth's physics and the Master used it to begin stealing the Doctor's lives. The Doctor helped Grace put the TARDIS in a temporal orbit, draining the power from the Eye and thwarting the Master. After the Master killed Grace and Lee, the Master fought the Doctor and fell into the Eye. The TARDIS reversed Lee and Grace's deaths and closed the Eye. (TV: Doctor Who)

The Fourth Doctor stopped the Y2K bug as the New Year arrived. (PROSE: Millennium Shock)

While Jack Harkness fought a "Millennium Bug" of his own, Alex Hopkins killed the rest of his Torchwood Three team, then himself after Jack returned, just as the New Year arrived in Cardiff's time zone. He had been driven insane by the Last of Erebus, which showed him dark things awaiting in the future. Hopkins tricked Jack to leave the Hub because he was immortal and would have prevented Hopkins' "mercy killings." Harkness subsequently took over Torchwood Three, given the leadership by Alex just before he claimed his own life. (TV: Fragments) Alex also spoke to Yvonne Hartman at Torchwood One of his epiphany beforehand on the phone, as he shot the team. This incident made her realise that the Torchwood Institute needed a stronger leader to face the 21st century. (AUDIO: One Rule)

Dave Young spent the entire evening trying to convince his girlfriend, Anji Kapoor, that the millennium wouldn't actually begin for another year. Kapoor, for her part, thought this extreme pedantry meant their relationship was in trouble. This incident led to her insisting on New Year's Eve 2000 that the two of them spend 2001 doing "Wild and Spontaneous Things' — the result of which was the couple spontaneously going to Belgium in February 2001. There, she met the Eighth Doctor and began travelling with him. (PROSE: Escape Velocity)

The renegade Time Lady Iris Wildthyme and her companion Panda arrived in San Francisco in her TARDIS. Immediately after their arrival, Iris spilled gin into the bus' control and out into the Time Vortex, resulting in various different versions of Panda from alternative realities crossing over into the primary universe. With the assistance of Dr George Strangeways, Iris was able to close the rift, though not before the Panda from the primary universe had been dragged into it. (AUDIO: The Panda Invasion)

"Dara Morgan" suddenly came into being, and registered MorganTech. He was broadcast live on a news channel that same day. (PROSE: Beautiful Chaos)

In an alternative timeline, the Fifth Doctor, Peri Brown and Erimem visited Edinburgh. (PROSE: Graham Dilley Saves the World)

Later years
In 2004, Rose Tyler missed a New Year's Eve party, thereby allowing her to unwittingly meet the regenerating Tenth Doctor prior to her first encounter with the Ninth Doctor on 4 March 2005. (TV: The End of Time)

In 2007, the Eighth Doctor and Charley Pollard arrived at 8:00, and witnessed New Year's Eve. They had intended to go to 1931, Charley's time, as she wanted to leave. The TARDIS had brought them to the wrong time because of a time hump on 17 January 1942. (AUDIO: The Girl Who Never Was)

In 2020, the European Space Agency's Mars rover Leonardo discovered a copy of David Bowie's Life on Mars which had been left on the planet by Erimem and Andy Hansen in 2016. Most of the rover's mission control had been celebrating New Year's Eve at the time, and only John Wilcox witnessed the find. Assuming it to be a prank by his colleagues, Wilcox did not record the rover's encounter with the album. (PROSE: Life on Mars on Mars)

In 2021, the Thirteenth Doctor, Yaz, Dan, Sarah and Nick were trapped in a time loop with a squad of Dalek executioners. (TV: Eve of the Daleks)

In 2066, Jack Harkness visited a bar on Zog. There, an individual of an unnamed species gave him instructions for the either earlier or later version of him. This version, upon opening a box on 7 August 1941, relived these experiences. (COMIC: Overture)

In 2599, a New Year's Eve party at the Braxiatel Collection was interrupted by murder. (PROSE: The Doomsday Manuscript)

Other
In 2018, Astrid Ferrier's helicopter registration was set to expire. (TV: The Enemy of the World)

The Eleventh Doctor left a homeless parent and child a slip of paper containing lottery numbers, dated to 31 December, for Christmas. (COMIC: Silent Knight)