[Image links to larger version which links to very large 968k graphics file.]
The picture is stamped as copyright the News Chronicle, and the Imperial War Museum believes that the officer is Admiral Sir Bertram Ramsey, who was Commander of Dover and responsible for the evacuation of Dunkirk. They also say that the helmet my father was wearing identifies him as a Stretcher Party Supervisor in the Civil Defence Services (aka ARP for Air Raid Precautions), which we did more or less know. He was in the ARP in London, I think throughout the war, and is possibly one of the sources for a story that Gerald Kersh wrote about the ARP whose title now escapes me - my father knew his publisher, and may have known Kersh although I'm not 100% sure about that. About the only thing I can add is that I think that the man on the extreme left has the words "Depot Supervisor" on his helmet, which to me suggests that the picture was taken at an ARP depot.
The trouble is that we have no idea when or where this was taken, or what the occasion for it was - records appear to be more or less non-existent, and so far the picture hasn't turned up in microfilmed archives of the News Chronicle at the British Newspaper Library in Colindale. It would be nice to know more.
Anyway, if anyone can shed any light on this, or suggest any sources we could try, I'd be grateful for their help. Please feel free to pass this on to anyone who might know anything relevant.