Who the devil is that? The chap who appears to be talking into a red 'L' shaped telephone? This image has been taken from routine surveillance footage during the episode of 'Checkmate.' He's not the Supervisor, he simply walks round, and round, and round the floor of the Control Room. What's more this short piece of film footage is simply inserted into different times in the episode when a long shot of the Control Room is called for. So I can only summise that the chap walking round the chamber, is standing in for the Supervisor in the long shots. As the actor Basil Dignam who plays the Supervisor in Checkmate, is only ever seen in the close-up shots!
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