Records of the Royal Air ForceAIR 251914-1996Air Ministry and Ministry of Defence: Operations Record Books, Groups
This series consists of Operations Record Books (form 540) and appendices (form 541) for RAF Groups. Operations Record Books (ORBs) are a record of daily events kept by units. The series also includes some ORBs for Royal Canadian and Indian Air Force Groups which served under RAF command during the Second World War. The system of Operations Record Books started after the First World War. Few Books in this series however date from before the mid 1930s, when the chain of command in the RAF was re-organised.