Planned as a grass airfield Relief Landing Ground for RAF Middle Wallop, Chilbolton was used as a fighter and Army Co-operation base during 1940-42. Enlarged and upgraded with a tarmac-surface hard perimeter track, some double blast pens and other fighter hardstandings, plus three blister hangars, the station was declared a full No. 10 Group satellite in April 1942. Allocated briefly to the 8th Air Force as a potential fighter base during August-September 1942, but never used by any 8th Air Force units, it was re-allocated to the USAAF in November 1942 as a potential transport or reconnaissance base, albeit built to bomber standard. The station was again enlarged and upgraded during January to December 1943 with three concrete runways, to become a 9th Air Force combined tactical air depot and operational base. Incomplete when the 5th Tactical Air Depot took up residence in January 1944, the existing perimeter track was extended and 48 new loop hardstandings were added to the existing dispersals. Two T2 hangars joined the existing blister hangars. Occupied by the 10th Air Depot Group from January to July 1944, and by the 86th Air Depot Group from January to September 1944, which specialised in the maintenance, modification and repair of P-47s, the station was also occupied briefly during March 1944 by the 12th and 15th Tactical Reconnaissance Squadrons, equipped with Spitfires and P-51s. The 368th Fighter Group, equipped with P-47s, operated from Chilbolton during March to June 1944, after which it was used as a casualty air evacuation and supply base by C-47s from various troop carrier groups. The 442nd Troop Carrier Group occupied the station briefly during September 1944, after which it continued to be used as a general USAAF transport staging base until handed back to the RAF in March 1945. Next used as a fighter operational training and fighter squadron base during 1945-46, the station closed in November 1946. It was occupied by Vickers-Supermarine from 1947 to 1957, and by Folland Aircraft from 1953 to 1961. The site was abandoned in 1961 and has since largely returned to agriculture, but the Space Research Council built the Chilbolton Observatory in the middle of the airfield during 1963-67. Part of the airfield remains operational with a private grass airstrip, home to the Chilbolton Flying Club.