This image is captioned as Mrs Iris Cynthia (no surname) of Kennington in the Lambeth borough of London but I cannot find any further information at this time.. It's very interesting as it is shows for the first time the use of District Wardens rank insignia (two red bars and diamond) on what initially looks like an ambulance drivers' coat. However, the buckle is not correct for that coat. It could be a private purchase wrap-over style item to which she has added insignia to. She has a 'DW' - District Warden - helmet.
News about interesting insignia, ARP related info and period photos that turn up.