AIR 291912-1996Air Ministry and Ministry of Defence: Operations Record Books, Miscellaneous Units
This series consists of Operation Record Books (form 540) and appendices (form 541) for units of the RAF other than Commands, Wings, Squadrons or Stations. Also included are some ORBs for Dominion Air Force units operating as part of the RAF during the Second World War. Although the system of Operation Record Books started after the First World War, few Books in this series date from before the mid 1930s.