Personnel have been employed in intelligence duties since the formation of the RAF in 1918. But the first dedicated RAF Intelligence Branch was established in late 1939 following the outbreak of the Second World War on 3 September. This model was also adopted by other Commonwealth nations. The new Intelligence Branch was initially called the General Duties (Admin) Branch but later renamed the Administrative and Special Duties Branch (for Intelligence duties). At the time, officers of the Intelligence Branch performed the duty of Squadron Intelligence/Protection Officer or aircrew on ground tours in the Air Ministry Intelligence Department. These officers were mainly trained pilots on a ground tour or who for medical reasons could no longer fly. In 1939 the Secret Intelligence Service also established a dedicated Air Intelligence Section under the command of Group Captain F. W. Winterbotham (Chief of Air Intelligence, MI-6). During the Second World War, the Intelligence Branch became larger to encompass the Signals Intelligence staff at Bletchley Park and the Imagery Intelligence staff at RAF Medmenham.