[Seyhall @replies]

Based on things in this episode I’m guessing Missy is The Rani ….

Wiki plot summary “The Doctor must recover his wits in time to avoid becoming a permanent part of the Rani’s plan to collect the genius of the greatest scientific minds in the universe, of which she has captured many including Einstein [was he on the train?]  in order that she can create a time manipulator, which would allow the Rani to control time anywhere in the universe”

and second, turn that GUS’ monocle anticlockwise and it starts to look like a pocket watch

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