Air Raid Wardens durin WWII

This is a subject on which I have yet to see.
Was anyone out there an Air Raid Warden during WWI? Perhaps your father or grandfather was. What did you learn from him as to what he did. All I know is that when a drill took place we had to cover our windows to keep any light from shining out, until the all clear sounded. These people had a flashlight with a paper covering the light and the letter E cut in the paper. To me, that seemed to have been an identifier that they were a member of the emergency air raid team, or whatever. I also remember when this happened (it was always at night)that many airplanes flew overhead. Today, years later,I have my thoughts about why that happened.