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Ringway was an officer on Briggs’ freighter in 2526.
He harboured a strong dislike for Captain Briggs because she ignored him. When everyone found out that he was working with the Cybermen, he held Briggs, Berger, Adric and the Fifth Doctor hostage.
When Scott and his troopers moved in and killed a few of the attacking Cybermen, the Cyber-Leader believed Ringway had lied to them and decided to kill him for his deceit. Once they arrived on the bridge, Ringway was killed without the Cybermen learning he had told them the truth. (Earthshock)