Brexit

Brexit was the process of the United Kingdom leaving the European Union in 2019. (PROSE: Lucy Wilson and the Bledoe Cadets)

The youth of 2016 considered it to be unstoppable. (PROSE: What She Does Next Will Astound You) Tyler Steele believed that it encouraged xenophobia such as that displayed by Red Doors in 2017. (AUDIO: Changes Everything)

In December 2016, after discovering that the Jezrafeq were controlling the minds of most of humanity, Andy Hansen jokingly asked Erimem, "You don't think this could explain Brexit and Donald Trump, do you?". Later, while tracing the source of the mind control signal, Andy suggested that the signal may have been coming from Trump Tower "because [Donald Trump] and Nigel Farage want[ed] to piss [Andy] off even more before the year end[ed]". (PROSE: Cliff Richard Saves the World)

The public were very unhappy with the handling of Brexit. Conall, Nick, Gordon and Kadiatu Lethbridge-Stewart all attended protest marches. (PROSE: Lucy Wilson & the Bledoe Cadets)

On 5 May 2018, Alistair Gordon Lethbridge-Stewart, while possessing the body of Hobo Kostinen, read a news article about Theresa May being encouraged to pursue a "no compromise" Brexit after UKIP voters flocked to Tories in local elections. He thought the term "Brexit" to be a ridiculous "buzzword". (PROSE: Lucy Wilson & the Bledoe Cadets)

According to one account, in 2018, UNIT dealt with budget issues brought on by Brexit. (PROSE: An Ordinary Man) By New Year's Day 2019, UNIT had been suspended due to "diverted funds". (TV: Resolution) Prentis told Kate Stewart that he had been fighting for UNIT to remain open, but that he had to give in (though as he was a spy for the Sontarans, he may have been responsible). (TV: Survivors of the Flux)

Behind the scenes
The Doctor Who: The Eleventh Doctor comic story Remembrance provides a parody of Brexit in the form of the planet Britzit-247. The part of Britzit-247 seen in Remembrance is a city with elements reminiscent of London which is populated by individuals who all resemble angry Nigel Farages and only say the word "Britzit". There's also a giant robot with the face of Boris Johnson. The Eleventh Doctor explains that Britzit-247 was founded by a group of Britons who "got cross about something or other" and decided to "travel across the stars" to start their own independent colony.

In 2019, Resolution established that UNIT operations in the UK were suspended, pending review, due to financial disputes, and "subsequent funding withdrawal by the UK's major international partners". It was widely reported, following broadcast, that Resolution was here making reference to Brexit.

In the DWU, the UK is still explicitly part of the European Union in AUDIO: The Longest Night, when the British Prime Minister signs the Euro-Combine Treaty. Even in this storyline, though, many see the strengthening of the "European superpower" as a threat to the UK's independence.

The UK later belongs to the Eurozone in AUDIO: Hothouse and PROSE: Trading Futures; Trading Futures remains vague as to when exactly in the early 21st century it's set, but the after-credits segment of Hothouse places that story before the events of The Eight Truths in 2015.