George F. Collier enlisted in the RAFVR May 1941 as an AC 2nd. class/Aircraft hand/ Observer. He was mobilised on the 11th August 1941. 4 months later (after basic/ trade training?) he re-mustered under training as an Observer and re classified as an Leading Aircraftsman. My question is- where did he spend those 4 months doing his basic training then his Observer training? Thank you, Roger Brown.