Of all the biographies written by wardens during the war, a couple continue to stand out to this day. One such tome is Barbara Nixon's "Raiders Overhead". Nixon's account of the Blitz in London, first published in 1943, is a compelling read and history of the times and how the ARP and Civil Defence Service worked. Well worth getting hold of a copy if you can. For more recommendations, see the resources section.
News about interesting insignia, ARP related info and period photos that turn up.