The episode focused primarily on Millie Gibson's former companion Ruby Sunday as she discovered that her boyfriend, Conrad Clark (Jonah Hauer-King), is actually a conspiratorial anti-UNIT activist – leading a group named Think Tank.
The name immediately rang a bell for longtime viewers, who recalled a shady gang with the same moniker first seen opposing the Fourth Doctor (Tom Baker) in a storyline named Robot.
In that episode, Think Tank used a robot to steal the destructor codes for the US, China and Russia's stockpile of nuclear weapons, and planned to start a nuclear war if the world didn't agree to its terms.
Now, screenwriter Pete McTighe has confirmed that viewers were right to match the two 'Think Tanks', as the inclusion was intended as a nod to the relatively obscure classic era antagonists.
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"Yes, Think Tank is a deliberate call-back to the story Robot from 1975," he told Doctor Who's official website. "I figured Conrad did his research, and stole the name of a previous organisation that opposed and clashed with UNIT."
In an impressive piece of attention to detail, the scene in which Conrad reveals himself to be affiliated with Think Tank also features an extract from the score of that classic episode.
On his inspiration for this reimagining, McTighe added: "Look around: We're living in a crazy world where misinformation has become currency and distrust is rife.
"That speech I wrote for the Doctor at the end of the episode – he says everything I wanted to say. I refer you to the Doctor."
While the end of Lucky Day saw Conrad humiliated, arrested and confronted by the Doctor, this won't be the last we see of him as Gibson has confirmed that she and Hauer-King will be back in time for the season 15 finale.
That tracks with what we saw in the final moments of Lucky Day, where an incarcerated Conrad was freed by the villainous and ever-mysterious Mrs Flood – but for what reason, we cannot say.
Next week's episode of Doctor Who, The Story and the Engine, will see the Doctor and Belinda travel to Lagos, where the mysterious Barber reigns supreme.
The synopsis for the episode teases: "The Doctor discovers a world where stories have power, but can he stop the Spider and its deadly web of revenge?"
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Doctor Who continues on Saturday 10th May, with the next episode becoming available from 8am on BBC iPlayer in the UK and airing at 7:10pm on BBC One. The series is available on Disney+ outside of the UK.
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