The term uniform was used to refer to the clothing worn for the purpose of displaying membership in an organization. During the Trojan War, Steven Taylor noted that, by taking a uniform, he would be captured as a prisoner of war instead of a spy. (TV: The Myth Makers)
In 2007, Gwen Cooper reported to her fellow Cardiff police officer Andy Davidson of a man in a porter's uniform being attacked by a man wearing a mask. (TV: Everything Changes)
During the 2000s, red caps constituted part of the uniform of UNIT soldiers. (TV: The Sontaran Stratagem/The Poison Sky) Reuniting with his old friend Martha Jones, now a member of UNIT, Jack Harkness jokingly asked if she could provide him with a red cap, suggesting that Ianto Jones would look good in one. Martha told Jack to get his own uniform. (TV: Reset) Bilis Manger noted how Jack was "not in uniform" when encountering him in 1940s war-time Britain, with Jack using the excuse that he was on leave for 48 hours. (TV: Captain Jack Harkness)
While working for Torchwood Three, (TV: Children of Earth: Day Four et al.) Captain Jack Harkness wore what Owen Harper described as a "military uniform." (TV: Fragments) His attire would earn him the nickname "World War II" from Rex Matheson. (TV: Rendition et al.)