The Wheel In Space
Armand Vallance was a member of the staff of Space Station W3 in 2079. He and Elton Laleham space-walked to the Silver Carrier and were mind-controlled by the Cybermen.
Vallance accidentally killed Laleham while trying to kill Sean Flannigan. He identified the station crew for the Cybermen but didn’t recognise the Second Doctor. He was released from the Cybermen’s mind control when Jamie McCrimmon and Flannigan placed a metal plate on the back of his neck. (The Wheel in Space)