The Next Doctor
Overhearing cries for help, he encounters a man calling himself "the Doctor" and his companion Rosita attempting and failing to capture a Cybershade.
The Doctor and Rosita find numerous children, pulled from workhouses around the city by Miss Mercy Hartigan, are being put to work at an underground facility under Cybermen guard.
The Cybermen betray Miss Hartigan, and convert her into the controller for the "CyberKing", a giant mechanical Cyberman powered by the energy generated by the children.
As the CyberKing starts to topple, the Doctor draws it into the Time Vortex with technology from Jackson's cellar, saving London.
[6] When writing the episode, Davies was unhappy with the final scene in which the Doctor gets rid of the CyberKing with the convenient Dalek dimension vault, but could not think of another way to stop London being crushed by a giant robot.
Later, after the episode was produced, he conceived an alternate ending in which Miss Hartigan "should have destroyed the Cybermen when she screamed... but she's still in the chair", as the CyberKing falls to the Earth, the Doctor calls out to her saying "Save them."
[7] David Morrissey is the main guest star, playing "a character called The Doctor – a man who believes himself to be a Time Lord".
[15] Dervla Kirwan plays Mercy Hartigan, who Russell T Davies describes in the episode's podcast commentary as "dark a villain as you will ever have".
A lot of her characterization goes unstated, but Russell discussed it in long conversations with Dervla Kirwan and fellow executive producer Julie Gardner.
Davies characterizes Miss Hartigan as "a victim of abuse", for whom the subtext suggests a "terrible backstory" which is symptomatic of her being "part of [this] Victorian Age."
Davies describes this as being "a powerless woman who's been in servitude or far worse all her life", but holds his tongue from saying her precise profession, relaying: "I'm talking quite discreetly around this because there are children listening and watching and there's only so far I should go."
"[7] Kirwan would later go on to voice Miss Quill, replacing the original actress Katherine Kelly, in the audio dramas of the spin-off Class produced by Big Finish Productions in 2019.
He sketched a new design for the Cybershade that was "a crude version of a Cyberman, all angular and blocky, with its trademark handlebars set at a jaunty angle and shrouded in flowing black robes".
The production team however worked hard, and in two days produced the final headpiece seen in the episode which Davies described as "beautiful", because it's "Victorian and it fits the design."
In the scene after the headpiece is placed on her, Dervla wore black contact lenses and SFX company The Mill helped to get rid of "any traces of white" in post-production.
[4] The episode had an Appreciation Index figure of 86 (considered Excellent), making it the second most-enjoyed programme on mainstream television on Christmas Day.
[22] The DVD features a full set of end credits newly produced in a "cinematic" format to replace the broadcast version.
