W/O Diffley was serving with 19 Operational training Unit B Flight. He was a crew member of Wellington X NC716 -0 which took off from Kinloss on a night training exercise. The aircraft was lost through worsening weather conditions.
Royal Air Force Bomber Command Losses of the Second World War: Vol. 7; Operational Training Units 1940-1947; W.R. Chorley; 2002; Midland Publishing; ISBN 1 85780 132 6
He is remembered in Birtley on B127.01
