Roots: Dr Peddler of Peddler Electronic Engineering is presumably named after Kit Peddler, co-creator of the Cybermen. There are references to My Old Man's a Dustman, McDonalds, Virgin Megastore, Darth Vader, Sherlock Holmes, Humphrey Bogart, the Marie Celeste, Winston Churchill, Roosevelt, Cadbury's Creme Eggs, Rentokill, Charlie Parker, Frankenstein, Dr Jekyll and Mr. Hyde, Aladdin, Hamlet, Rage Against the Machine, Casablanca and D.H. Lawrence. The Doctor sings Colonel Bogey.
Dialogue Triumphs: The Doctor: 'I've been the manipulator for too long, moving the pawns, the chessmaster. I've spent so long formulating my own schemes that I've missed the fact that there are others better versed in the art of deception and deceit.'
'Sometimes I'm appalled by my own recklessness.'
Memorable Moments: The gory conclusion to Part Three sees the Doctor bursting into the Cyber base to find humans in various states of conversion, including a baby.
Continuity: The Cybermen seen here are of the Late CyberFaction type seen in The Wheel in Space [they have teardrop eyeholes, but the Doctor notes that they are far more advanced than Cybermen in this era should be, the nearest Cybermen to this era being those seen in The Invasion]. They travel to 1940 from the thirtieth century as part of a time travel experiment, a Cyberleader sent on ahead to prepare a hiding place for an army of sleepers, waiting to be reactivated at an appropriate time. The Cybermen retain an immune system; the Limehouse Lurker's collapses due to damage, sending it into an insane frenzied blood lust. Their Time Machine is an experimental model, and the calibrators that they used to navigate malfunctioned, stranding them in London on the eve of the Second World War. The Doctor describes the Time Machine as dangerous and suggests that it could cause a tear in space-time and tells Ace that it is so badly designed that he could never get it working properly. When Limb activates it, it causes time distortion, slowing time down around it, and shreds Limb through time and space. Only two or three arrived in the capsule, including the Cyberleader, plus their command-relay unit. The Doctor describes the Cybermens' command-relay unit as a mobile battle computer. It is a waist-high robot, with a flat circular upper surface and a rounded underside from which a pair of short flexible legs protrude. It generates a force field around itself and the triggers a plasma explosion outside of the field, presumably for self-defence. The Cybermen convert a baby, grafting full-sized arms onto its torso and replacing its legs with a large, Cybermat-like tail. Following the defeat of the Cybermen a massive sleeper army remains dormant in the London sewers [they are possibly found and modified by the Cybermen of The Invasion].
Cybermats are capable of burrowing into a human chest, resulting in wounds similar to those caused by a stabbing. Different types have different weapons, including sonic waves (The Wheel in Space), or the ability to inject poison (Tomb of the Cybermen). Those used here possess lethal metal teeth and are used as dissection tools during Cyber-conversion. They are have been created on Earth during the era from rodents, including a red squirrel. Because the brains of Cybermats are based on those of primitive animals, they are unpredictable in any given situation. They can track humans by scent.
The Doctor's pockets contain an Arcturan gambling chip and a pair of false teeth. To hide himself and McBride from the Cybermen and Cybermats he sets up a jamming signal that disguises their biorhythms. He carries a UNIT pass dated 1980 and featuring either his Third of Fourth incarnation. He is immune to the effects of the time distortion caused by Limb's use of the Time Machine (see Invasion of the Dinosaurs).
Ace knows enough about guns to recognise McBride's as a Browning nine-millimetre. She dislikes the hard edge that enters the Doctor's voice whenever he mentions Daleks. She has been pestering him for days to let her make an improved nitro-nine in the TARDIS lab.
Links: Silver Nemesis. There are references to Ace's Grandmother, Kathleen Dudman (The Curse of Fenric), plus her old friends from Perivale (Survival). Manisha was first mentioned in Ben Aaronovitch's novelisation of Remembrance of the Daleks. There is a reference to Ace's dislike of Clowns (The Greatest Show in the Galaxy). Ace has a bar-towel with Welcome to Iceworld on it (Dragonfire). The Doctor mentions the Dalek invasion (The Dalek Invasion of Earth). When he reprograms the command-relay unit he uses the authorization code Theta Sigma (The Armageddon Factor, Christmas on a Rational Planet). There is a reference to Sontarans.
Location: London and Jersey, over several days from 13th November 1940.
Unrecorded Adventures: The Doctor reveals a hitherto unrevealed fondness for baseball having seen Babe Ruth hit three home runs in a single-game in 1926. He has seen the Pittsburgh Crawfords many times.
The Bottom Line: An effective use of the Cybermen, nicely evocative of the television era it follows on from. George Limb is an interesting, well-characterised villain, and there are some truly disturbing moments that demonstrate the body horror represented by the Cybermen.