I am indebted to Michael Newbold for the following photo of Kingston Upon Thames ARP first aid personnel taken at Bonner Hill School. The people present are probably all members of the St John Ambulance attached to ARP duties. You can see ARP window notices on the windscreens. There are a smattering of dark armbands present but I cannot clearly identify if these are St John variations (or even the dark green Red Cross ARP armbands). There are a few ARP lapel badges and I think one gentleman appears to be wearing the First World War Silver Wound Badge.
News about interesting insignia, ARP related info and period photos that turn up.