An air raid warden was a civilian official in Britain during World War II. One of a warden's chief duties was to ensure that the citizenry were observing blackout procedures, so that German night time bombers would not be able to easily identify targets below them.
One such warden was stationed on the top of the building that housed the Cabinet War Rooms. He was particularly alarmed by the fact that London lit up just prior to a German air raid. Unbeknownst to him, the lights were turned on by Daleks orbiting the Earth. (TV: Victory of the Daleks)