Before the building of an airfield, Greenham Common was mainly common land with a few houses and a pub. It was used for troop movements during the English Civil War and in the eighteen and nineteenth centuries.

In late 1943, Greenham Common airfield was turned over to the USAAF Ninth Air Force. An American advance party soon arrived to ready the airfield for the incoming units. Greenham Common was known as USAAF Station AAF-486 for security reasons by the USAAF during the war, and it was referred to by this name instead of by location. Its USAAF Station Code was "GC".

The first arrival was the 51st Troop Carrier Wing Headquarters, arriving in September 1942. The 51st TCW controlled the three troop carrier groups at RAF Keevil (62nd TCG), RAF Aldermaston (60th TCG) and RAF Ramsbury (64th TCG) as part of Twelfth Air Force. The Wing Headquarters was located in requisitioned Bowdown House, a mansion on the northeast end of the airfield, and made use of the runways for its communication and courier flights.

The 51st TCW HQ followed its groups to North Africa as part of Operation Torch in November 1942.

Rumours and intrigue

On 28 February 1958, a B-47E of the 310th Bomb Wing developed problems shortly after takeoff and jettisoned its two 1,700 gallon external fuel tanks. They missed their designated safe impact area, and one hit a hangar whilst the other struck the ground 65 feet (20 m) behind a parked B-47E. The parked plane, which was fuelled, had a pilot on board, and was carrying a 1.1 megaton (4.6 PJ) B28 nuclear bomb, was engulfed by flames. The conflagration took sixteen hours and over a million gallons of water to extinguish, partly because of the magnesium alloys used in the aircraft. Although two men were killed and eight injured, the US and UK governments kept the accident secret: as late as 1985, the British government claimed that a taxiing aircraft had struck a parked one and that no fire was involved.

Two scientists, F. H. Cripps and A. Stimson, who both worked for the Atomic Weapons Research Establishment at Aldermaston, alleged in a secret 1961 report, released by the CND in 1996, that the fire detonated the high explosives in the nuclear weapon, that plutonium and uranium oxides were spread over a wide area (foliage up to 8 mi (13 km) away was contaminated with uranium-235) and that they had discovered high concentrations of radioactive contamination around the air base.

However, a radiological survey commissioned in 1997 by Newbury District Council and Basingstoke and Deane found no evidence of a nuclear accident at Greenham Common, suggesting that Cripps and Stimson's claims were false. The seven-month long survey was carried out by the Geosciences Advisory Unit of Southampton University and combined a helicopter-mounted gamma ray detector survey with a ground-based survey. The team analysed nearly 600 samples taken from soil, lake sediment, borehole water, house dust, runway tarmac and concrete, looking for uranium and plutonium isotopes. No evidence of an accident involving nuclear weapons damage was found at the former air force base although the ground survey detected some low-level uranium contamination around the Atomic Weapons Research Establishment at Aldermaston thought to be derived from that facility, and the helicopter survey found some anomalies around Harwell Laboratory.

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