This portrait, from a series of staged photos, shows a Warden from the Westminster area of London. She's wearing the standard issue ARP Pattern 71 tunic with slacks. The tunic features the ARP embossed buttons (tunics are also known to have white metal CD and crown and from 1943 black plastic buttons featuring CD letters and crown). She's has a civilian style respirator sack slung over her shoulder and the lanyard is probably white (boroughs of London generally adopted this colour).
News about interesting insignia, ARP related info and period photos that turn up.