More information : RAF Caistor was constructed in 1940 as a relief airfield with grass runways for RAF Kirton in Lindsey. By 1942 it was used by the Advanced Flying Unit (no.15 P) under the control of RAF Kirmington. Its location, in the Lincolnshire Wolds, meant that it was best suited to a day only training role. Flying ceased in 1944 and the airfield finally closed in 1945.
The old Caistor airfield found a new military purpose in 1959, when it became a satellite Thor missile site under the control of RAF Hemswell, Lincolnshire. Thor missiles were the first operational Intermediate-range Ballistic Missile (IRBM) system deployed by the West during the Cold War. With a range of 1,500 nautical miles, Thor missiles were approximately 20m (65ft) long and 2.5m (8ft) in diameter powered by propellant rocket fuel controlled by two motors. Developed by the United States (US) Government between 1955 -1959, the proposal to deploy Thor in Britain as well as the US was put before the British Government in 1957. At the time Britain was developing its own IRBM, Blue Streak, which would not be operational for some time. Final agreement to locate Thor in Britain was reached between the Prime Minister, Harold Macmillan, and President Eisenhower at the Bermuda Conference in 1957. The rockets were to be British property, manned by the RAF who would be trained for the task by the USAF, but the nuclear warheads would remain under US control. Macmillan reported to Parliament that the decision to use Thor against the Communist east would be made jointly by the two countries.
A total of 60 missiles were deployed at 20 sites in the East of England from 1958 under the codename 'Project Emily'. There were four main bases located on pre-war permanent airfields; RAF Feltwell, RAF North Luffenham, RAF Hemswell and RAF Driffield. At each base an adapted hangar was used to receive the missiles, store the servicing equipment and conduct inspection and maintenance. Usually located on the opposite side of the airfield, the Thor compounds at the main bases had a Surveillance and Inspection Building and a Classified Storage Building, partly surrounded by earthwork berms, where the warheads were inspected and stored. Every main base had four satellite stations, each with their own Squadron. The launch areas at the main and satellite stations were almost identical, although at the latter a smaller Classified Storage Building and Pyrotechnic Store was placed c 200m away from the nearest emplacement, protected by earthwork banks. The buildings and emplacements lay in an irregularly shaped compound surrounded by a pair of fences. Inside were crew huts, a squadron office and telephone exchange. Close to the main gate was the launch control area, an area of concrete on which the control trailer, generators and an oil tank were placed.
Exact siting of the missiles was essential to ensure the targets were reached. In addition to the precise, fixed location of the launch components each emplacement had a theodolite shed and a separate long-range theodolite set on a concrete pillar surrounded by brass survey points. At the opposite end of the emplacement two short-range theodolites were mounted on a metal platform near to the launcher erector which lay at the centre of each emplacement and was secured to a metal cage set in concrete. Here the missiles, which were stored horizontally on a trailer, were raised to a vertical position. The two fuels which powered the rocket, kerosene and liquid oxygen, were stored in fuel pits on either side of the erector and pumped separately through pipes suspended in concrete conduits. A separate liquid oxygen dump tank was located to the rear of the blast walls in case the fuel needed to be rapidly discharged from the missile. At the far end of each emplacement were two 'L' shaped blast walls.
Thor missiles could be brought to operational readiness in 15 minutes after receiving the authorised and authenticated order to launch. Strict understandings about the operational control of the missile included an agreed British and US launch through a dual key system and a veto for each Government. Although Thor deployment in Britain was an interim measure, their presence played an important part in the Cuban Missile Crisis of October 1962, the most tense period of the Cold War, when fifty nine of the sixty missiles were made ready. Thor was phased out in England between April and August 1963, just short of their anticipated 4 year life-span, North Luffenham being the last site to close.
At Caistor, the airfield and Thor missile site quickly reverted to agricultural use. The site is used for poultry farming with large bird-breeding sheds located on the concrete pads of two emplacements. Some of the World War II and Thor site ancillary buildings remain. However, agricultural reservoirs and conifer planting have been established within the Thor compound.
MATERIALS
Concrete with metal fixings.
PLAN
Each emplacement is aligned approximately east-west and comprises a central concrete pad for the launcher erector and blast walls at the east end. The three emplacements have a roughly triangular configuration overall.
EXTERIOR
Access to the Thor site appears to have been from the western perimeter track where some ancillary buildings are located, possibly a fire tender building and crew rooms. The Classified Storage Building and Pyrotechnic Store is not thought to survive. The access road to and between the emplacements remains, but has been extended to facilitate the current site usage. As a result, a road has been laid along the length of the eastern emplacement.
Each emplacement retains its blast wall and at least one of the fuel pits. Some of the shelter rails remain, but none of the launch erector or short-range theodolite mountings or theodolite sheds survive. Both the south and west emplacements have been curtailed, their concrete seemingly grubbed-out.
SOURCES
Boyes, J, Project Emily: Thor IRBM and the RAF (2008)
Cocroft, W and Thomas, R, Cold War: Building for Nuclear Confrontation 1946-1989 (2003)
Wilson, J, Launch Pad UK: Britain and the Cuban Missile Crisis (2008)
www.harringtonmuseum.org.uk, accessed 20th October 2010
The Thor missile site at former RAF Caistor, Lincolnshire, is not recommended for designation for the following principal reasons:
* Intactness: Most of the characteristic structures of the Thor missile site have been truncated or removed.
* Historic Interest: The fragmentary, physical survival of the Thor site at the former RAF Caistor does not illustrate the international historic significance of Thor missile sites in England. (1)
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