A nabbed this silver ARP badge on eBay for a fiver recently. Though quite unofficial a number of silver makers manufactured these smaller versions of the lapel badge. This example is by Bl,Bs, (Bendall Brothers) and has the Birmingham anchor and silver lion marks. The date letter is an O which corresponds for Birmingham to 1938 and goes to show they were being made very early on.
Read a history of the ARP badge
News about interesting insignia, ARP related info and period photos that turn up.