An interesting photo showing the rescue of a dog. The white helmet on the right is most interesting as he has both the ARP breast badge as well as the 'R London' badge on the pocket of his bluette overalls. The photo is said to be from 1940 which tallies with the overalls and lack of the serge battledress. I currently don't know the exact date that the 'R London' badge was introduced but going by this photo is was quite early in the war.
News about interesting insignia, ARP related info and period photos that turn up.