 In a flashback sequence in one of his early episodes , Lucas is subjected to waterboarding , a method of psychological torture . In order to ensure the authenticity of the sequence , Armitage was himself subjected to the actual torture while shooting . He agreed to perform the sequence after he was convinced by consultants for the FSB and CIA . Armitage was only subjected to it for a short time , and was filmed in slow motion to make it appear he was on for longer . The ambient temperature of the room was also raised to make him as comfortable as possible . However , after the sequence was shot , Armitage changed his opinion entirely , stating ; " I only lasted five to ten seconds , and the sound of my voice crying out to stop isn 't me acting . " Armitage shot more interrogation scenes during production of the eighth series , but only some were added into the episodes . He was " less physical " in the ninth series . 
