I was recently in a charity shop and picked up "The Royal Family in Wartime". There were of a number of photos of the family visiting bomb damaged areas and the below is one such. It shows the King's wife (later Queen Mother) in Plymouth. The interesting part is the way the warden has attached his whistle to the chin strap of his helmet. A novel way of wearing it but you would think that it swaying about when not in use (most of the time) would be a right pain.
News about interesting insignia, ARP related info and period photos that turn up.