Roots: In the Bleak Midwinter, While Shepherds Watched Their Flocks By Night. Pat and Lucie imitate Lady Penelope and Parker from Thunderbirds. Santa Claus is Coming to Town ("he's making a list, he's checking it twice"). The Zygon parabolic diverter's function as a 'hitching' device is similar to that of Ford's gadget in The Hitchhiker's Guide to the Galaxy. The Sixth Sense ("we see dead people?"). The Doctor says he is "not Superman - I haven't got x-ray eyes, I can't leap tall buildings in a single bound". There is a possible gag in the waking Lucie imagining she is in Holby City (Sheridan Smith had a short role in the TV series), while the Doctor's description of his appearance as a "ponce" may be a nod to an insult cast at his character in Withnail & I. Could the hospital Christmas card from "Stubbsy, Banksy and Barnesy" be a name check to Una Stubbs (The Horror of Glam Rock), Zygon creator Robert Banks Stewart and Alan Barnes?
Technobabble: A parabolic converter locates the energy forms of an alien creature.
Dialogue Triumphs: "What about doctors?" "-She's got a Doctor!"
Continuity: Lucie once had a boyfriend who was diabetic. Her home address is 46 Cheney Road, Blackpool. In 2008 she is already living there, having not yet met the Doctor. She has never heard of Siouxsie and the Banshees
As Pat, Hagarth ought to look in her early thirties, but photomelanoma, a mutation of a Zygon's photoreceptor cells after staying in one form for too long, has taken its toll and he is dying, with his outward appearance as 'Auntie Pat' looking somewhere in her Fifties. With Hagarth's link to the Zygon ship and Skarasen broken, he cannot treat the mutation or recover. Zygons don't have coccyxes.
A Zynog is a Zygon offshoot, more correctly a Zygon criminal who has been cast out of society for breaking one of its fundamental laws, forbidding the stealing of another Zygon's bioprint. Contained in rough, primitive bodies without the ability to shapechange they seek other life forms, selecting the downtrodden and those low in morale, who might easily be persuaded to surrender control of their bodies. The Zynog here followed Hagarth's crew to Earth, using the remains of their spaceship to create a new body replication machine and a parabolic converter to detect the presence and location of another Zygon (Hagarth stole it) It also uses a diadem, which generates the trance state required by the alien to enter another mind (it's handy that it then leaves it lying about for the Doctor to use).
Links: The Horror of Glam Rock (the TARDIS initially lands next to the same service station in Bramlington from that story), The Zygon Who Fell to Earth. The Doctor mentions Cal-Med One and the Bi-Al Foundation (The Invisible Enemy)
Untelevised Adventures: The Doctor says he once rode a magic carpet over the Khyber Pass.
Location: Blackpool, 2008.
The Bottom Line: "What is this, Give Lucie a Downer Day?"
Doctor Who does Christmas, Eastenders-style. Though it was seemingly signposted back in 2008 in an otherwise unassuming Zygon gambit, the resolution to the Aunty Pat trilogy is a nasty sting in the tail of Lucie's time with the Doctor. There's humanity here, and you have to have a heart of dwarf star alloy not to enjoy John Glover's Santa; but this is a gloomy story, folks, and as much a tale of betrayal as any Alan Barnes script with a companion departure and/or a comedy alien or two. Truth be told, the Zynog is a naff name - and this is no RTD-Era seasonal romp. As companion departures go, it's one of the sad ones - best not listen to this one alone, maybe.