Unit History: RAF Medmenham

RAF Medmenham was a Royal Air Force unit based at Danesfield House near Medmenham, in Buckinghamshire, England. The unit specialized in photographic intelligence, and was once the home of the RAF Intelligence Branch. RAF Medmenham was to imagery intelligence, what Bletchley Park was to signals intelligence.

In April 1941 an RAF photographic interpretation unit (PIU) moved to Danesfield House, Medmenham, as its previous location at Wembley was short of space, and was renamed the Central Interpretation Unit (CIU). Later that year the Bomber Command Damage Assessment Section was absorbed, and amalgamation was completed when the Night Photographic Interpretation Section of No 3 Photographic Reconnaissance Unit, RAF Oakington, was integrated with CIU in February 1942.

During 1942 and 1943 the CIU gradually expanded and was involved in the planning stages of practically every operation of the war, and in every aspect of intelligence. In 1945 daily intake of material averaged 25,000 negatives and 60,000 prints. By VE-day the print library, which documented and stored world-wide cover, held 5,000,000 prints from which 40,000 reports had been produced.

American personnel had for some time formed an increasing part of the CIU and on 1 May 1944 this was finally recognised by changing the title of the unit to the Allied Central Interpretation Unit (ACIU). There were then over 1700 personnel on the unit’s strength. The title of the unit reverted to Central Interpretation Unit when the Americans returned home in August 1945.

Early in 1945 a number of photographic interpreters (PIs) were sent to join the British Bombing Research Mission in Paris to explore the degree of damage and production interruption caused by Allied bombing in the Resistance areas of the Central Massif and in the ports. They were also tasked with checking PI reports which would eventually be related to assessment reports of attacks on German industry. Several PIs were also seconded to The Pentagon in Washington, D.C. to join a detachment of RAF and Army Officers.