Seems that PO Prune had a relative in the Navy?
Photo is of Lancaster 1 W4118/ZN-Y of 106 squadron at Syerston in November 1942.. Guy Gibson often flew this plane when the squadron CO though the pilot shown is PO Jimmy Cooper.
106 Squadron often laid sea mines and so had several naval officers attached which lead to several of their aircraft getting 'Admiral' prefixed nicknames.
'Admiral Prune' was lost 4/5 February 1943 on a raid to Turin.