A lot of thought and effort went into creating the badges worn by Civil Defence Services in WW2. The initial colour of red badges was thought to be too closely aligned with the fire services and so the gold and blue badges were created when the new serge uniforms were issued in the autumn of 1941.
There were many discussions about prospective badges and the design below was for a metal ARP cal badge. Similar in many ways to the RAF badge this would have been affixed with two lugs and a split pin. However, due to reasons of economy and the fact that the new service was to be known as the Civil Defence Services this particular badge was created.
News about interesting insignia, ARP related info and period photos that turn up.