Chalgrove Airfield Chalgrove Airfield is a former Second World War airfield in Oxfordshire , England . The airfield is located approximately north - northeast of Benson ; about north - northwest of London . Opened in 1943 , it was used by both the Royal Air Force and United States Army Air Forces . During the war it was used primarily as a combat reconnaissance airfield . After the war it was closed in late 1946 . Today , the airfield is primarily used by the Martin - Baker company for testing ejector seat s . History . United States Army Air Forces use . Chalgrove was allocated to the United States Army Air Forces ( USAAF ) by the Air Ministry on 1 November 1942 . It was known as USAAF Station AAF - 465 for security reasons by the USAAF during the war , and by which it was referred to instead of location . 10th Reconnaissance Group . The first residents of the airfield was the 10th Reconnaissance Group which arrived from Key Field , Mississippi in January 1944 . The group consisted of the following operational squadrons : The 30th Photographic Reconnaissance Squadron ( PRS ) arrived in January and early February . The 31st , 33rd and 34th PRS became operational at Chalgrove in April . The primary aircraft flown by the group consisted of photographic versions of the P - 38 Lightning ( F - 5 ) and P - 51 Mustang ( F - 6 ) . In addition the unit also flew the Stinson L - 1 Vigilant and L - 5 Sentinel along with the Piper L - 4 Grasshopper light observation aircraft . In May 1944 the 30th PRS moved to RAF Middle Wallop and it was replaced by the 423rd Night Fighter Squadron with A - 20 Havocs ( F - 3A ) from RAF Charmy Down which was used for night photo reconnaissance . In June the 423d was renamed the 155th Photo Reconnaissance Squadron . After the invasion the 15th TPRS moved into France first , to the Advanced Landing Ground at Rennes - St - Jacques , France ( ALG A - 27 ) on 10 July . The other squadrons of the 10th moved over the next few weeks , the last being the 155th which moved to France in mid - August . 25th Bombardment Group ( Reconnaissance ) . In August 1944 the 653d Bombardment Squadron of the 25th Bombardment Group based at RAF Watton moved to Chalgrove . The 653d was an Eighth Air Force unit equipped with special weather reconnaissance Mosquito PRXVI ' s which operated over the waters adjacent to the British Isles and occasionally to the Azores to obtain meteorological data . The squadron also flew over mainland Europe for weather information needed in planning operations . In November 1945 the squadron was inactivated . 7th Reconnaissance Group . In March 1945 the 13th , 14th and 22nd Photographic Reconnaissance Squadrons from the VII Air Service Command 7th Reconnaissance Group moved to Chalgrove from RAF Mount Farm flying P - 51 Mustangs ( F - 6 ) . Fuselage codes for the 13th PRS was " ES " and " G2 " for the 22d . The unit also flew the Stinson L - 5 Sentinel light observation aircraft . The group was inactivated at the 4th Strategic Air Depot ( Hitcham ) on 21 November 1945 . Royal Air Force use . With the inactivation of the 25th Bomb Group , the USAAF returned the airfield to the RAF on 1 December 1945 . Current use . With the end of military control , Chalgrove Airfield was leased by the MoD to Martin - Baker in July 1946 for development and testing of ejection seats . Today the airfield is surrounded by very high fences and access is restricted . Although most of the hardstands have been removed over the years , all of the runways and perimeter track exist and are still in use by Martin - Baker . Two of the wartime T - 2 hangars are in use as part of the airfield and the Monument Industrial Estate site just to the southeast of the airfield contains some old USAAF buildings that were once part of the airfield . Chalgrove Aerodrome has a CAA Ordinary Licence ( Number P683 ) that allows flights for the public transport of passengers or for flying instruction as authorised by the licensee ( Martin - Baker ( Engineering ) Limited ) . The aerodrome is not licensed for night use . Runways 06 / 24 and 18 / 36 became unlicensed in 2012 . In popular culture . Chalgrove appeared in an episode of the British TV series " The Professionals " , the Cessna 172 being used by an escapee supposedly crashing into an airfield building . An episode of the cult series " The Prisoner " also used Chalgrove , including sequences involving a Martin Baker Gloster Meteor .