(Photo: BBC America)
The story so far: The Doctor has been split from Yaz and Dan (stranded in 1904), and chased through a village of Weeping Angels. The universe is being eaten by space clouds and time is unravelling. Bel and Vinder are still no nearer finding one another, and guess what? The Doctor has been turned into an Angel. Things are, not to put too fine a point on it, tense.
“Survivors of the Flux” is a dazzling narrative in which the catastrophic threads of the Flux tale are laid against an older Doctor Who story – that of the Doctor’s time with the Division. It reintroduces Tecteun, a key character from her past and then almost immediately takes her away again. And it starts with the Doctor as a statue.
Here are a few things to bear in mind, the next time you watch:
1. British audiences will be well familiar with the face of Barbara Flynn, who plays Tecteun/Awsok. She has a long and well established career as a character actor, appearing in the very popular comedy show Open All Hours, and the comedic detective drama The Beiderbecke Affair. She’s also provided voices for the Big Finish audio adventures “Secrets of Telos” (playing Professor Vansom), “The Skull of Sobek” (Sister Chalice/Croc Trooper) and the Torchwood One story “The Rockery (Anne Hartman).

2. This is the first Doctor Who TV story to establish some form of early backstory for the establishment of UNIT, the United Nations Intelligence Taskforce. Previously, all we’ve known is that it was up and running by 1966, when the Cybermen attacked London in the Second Doctor story “The Invasion”. By having General Farquar and Prentis/The Grand Serpent discuss the formation in 1958, it gives eight years for the taskforce to become fully operational.
3. General Farquar is played by Robert Bathurst, another very familiar face for British TV watchers, most notably for his role as the pompous management consultant David Marsden in the comedy drama Cold Feet. As well as a long list of other TV appearances in shows such as Downton Abbey, he had a prominent role in the (unaired) pilot episode of Rowan Atkinson’s celebrated historical comedy The Black Adder, made a brief appearance in the first episode of Red Dwarf and made his 1991 TV breakthrough in the sitcom Joking Apart, written by Steven Moffat.
4. Farquar mentions events at the Post Office Tower, an iconic London landmark – still under construction at the time – that formed a key focus of the First Doctor story “The War Machines.”
5. During the scenes in which UNIT is established, we can hear some audio of  Nicholas Courtney as the Brigadier – leader of the taskforce in the 1970s, commanding officer of the Third Doctor and father of Kate Stewart – saying “Lethbridge-Stewart here. I want a call to the RAF, please.” It is actually taken from the 1971 Third Doctor story “Terror of the Autons.”
6. It’s tempting to see the events in this story as a way of finally putting to bed one of the most confusing parts of classic Doctor Who’s storytelling, namely the actual years in which UNIT was operational. “The Invasion” was set in 1979, the Third Doctor’s various adventures with Earth-bound aliens were left chronologically ambiguous, but by 1983’s “Mawdryn Undead” (as in, the year viewers were watching) the Brigadier could be found telling the Fifth Doctor he had retired in 1976 – three years before his first encounter with the Cybermen. It’s not clear if this new narrative fixes matters, though.
7. Also not helping, General Farquar refers to Lethbridge-Stewart as “our new corporal,” a rank he is not known to have held. When the Doctor first meets him in “The Web of Fear,” he is a colonel, an officer rank only open to those who have been trained at the Royal Military Academy Sandhurst or in the University Officers' Training Corps. 
Corporal is a soldier rank, attainable after around 6-8 years in service. As this part is set in 1967, and Lethbridge-Stewart is promoted to Brigadier by 1968 (a jump that isn’t possible from corporal within British Army hierarchy), we can only conclude that it’s a slip of the tongue by the amiable General.
8. Apart from his "appearance" in the Twelfth Doctor story “Death in Heaven” as a reanimated corpse within a Cyberman, and being the intended recipient of a telephone call from the Eleventh Doctor in “The Wedding of River Song,” the Brigadier hasn’t been in Doctor Who since the 1988 Seventh Doctor story “Battlefield”.
Nicholas Courtney did reprise the role once in the modern era, appearing in The Sarah Jane Adventures story “Enemy of the Bane” in 2008, as a last-minute stand-in. Russell T Davies had wanted a team-up between Sarah Jane Smith and Martha Jones, but had to reconsider when it became clear that Freema Agyeman’s commitments to Law and Order UK were too great.
9. When called out for constantly banging on about being Liverpudlian, Dan responds with a very area-specific zinger: “All right, Sheffield, keep your cutlery on.” This is a reference to the reputation of Yaz’s hometown for producing fine steel, including stainless steel knives, forks and spoons.

10. Ready to go out on a fan theory? Of course you are. Remember the floating house that the Doctor visualized in “War of the Sontarans”? Some hardcore Whovians have been wondering if it’s a nod to a book called Lungbarrow, based on a script written by Marc Platt for the Seventh Doctor.
The book invented a family backstory for the Doctor, and claimed our favorite Gallifreyan grew up in a gothic pile called Lungbarrow, and that the Time Lords were actually grown in looms, located within the house. 

@DrOho made the link in this tweet: 

And as we do at least get to see the Doctor speaking to her “mother” Tecteun, it’s not so very far-fetched to conclude that Chris Chibnall intended the floating house to be a nod to Lungbarrow, even if it doesn’t explicitly make that story part of TV canon.
Have you learned anything new about Doctor Who's "Survivors of the Flux"?