Halifaxman is correct in this, LAC tended to be a ground trade with Flight Sergeant and above in aircrew. group had many stations in the Vale of York and Topcliffe was mainly a training station housing HCUs (Heavy Conversion Unit). Given the number of stations and aircraft in quite a small area, the skies above North Yorkshire and the Vale must have been rather crowded in the 1940's.
Totaly as an off topic bit, Topcliffe was my late father's last posting and I still live in a neighbouring village within sight of the 'c' type hangars. My daughter kept her horse at the Artillery Barracks saddle club which housed the horses in converted bomb stores!
