AIR 27
Title: Air Ministry and successors: Operations Record Books, Squadrons

Record books in this series provide a daily record of events in each squadron entered on Form 540, with appendices including some photographs (many of which may have different covering dates from those of the books themselves).

Also included are some Operations Record Books (ORBs) for Dominion and allied air force squadrons under British command. Though the system of Operations Record Books started after the First World War few books in this series date from before the mid-1930s.  

Physical description: 4033 files and volumes