Scheduled Ancient Monument: Orford Ness: the Atomic Weapons Research Establishment test buildings and associated structures (1416933)

Reasons for Designation Laboratories 1, 2 and 3 and the Control Room to Laboratory 1; the Vibration Test Buildings and their Centrifuge, Control Room, Magazine and Hard Impact Facility, constructed between 1954 and 1962, on Orford Beach, are scheduled for the following principal reasons: * Rarity: the buildings on Orford Beach are rare, perhaps unique, nationally and internationally; * Diversity: the site has a high diversity of component buildings and structures each with a bespoke design for undertaking specific testing regimes; * Survival: the buildings and structures survive well and reflect the evolution of the experimental technologies tested here; * Documentation: the military site at Orford Ness is well documented and researched, underpinning the assessment of national importance. History Orford Ness is sited on the Suffolk coast; it is the largest vegetated shingle spit in Europe and stretches for about 10 miles (16 km) with a maximum height above sea level of around 4m (13ft). To the west the spit is separated from the mainland by the River Alde-Ore. The spit is divided into two by a channel known as Stony Ditch, aligned north-south. Prior to the C20 Orford Ness was a rarely visited place; the main economic activity was animal grazing on reclaimed marsh land. In 1915 the Armament and Experimental Flight of the Royal Flying Corps (later known formally as the Aircraft Armament and Gunnery Experimental Establishment) established a flying field on King’s Marshes to the west of the ditch, now known as the Airfield Marshes, serviced by a range of ancillary buildings arranged along a single track known since 1993 as ‘The Street’, on which ran a narrow-gauge light railway which led back to the jetty. Its main areas of investigation were the evaluation and suitability of aircraft, machine guns and gun sights, bomb sights, night flying and navigation, and a huge range of research projects to solve technical difficulties encountered in action. From 1924 the airfield was re-occupied as a satellite station of the Airplane and Armament Experimental Establishment based at Martlesham Heath. During their tenure, a number of structures were constructed on Orford Beach. Due to its remoteness one of the main activities at Orford Ness was the investigation of bomb ballistics; the study of the flight of objects moving under their own momentum and the force of gravity. Other experimental work continued into the inter-war period on Orford Ness. In 1935, a small experimental radar team arrived and conducted experiments that were critical in proving the value of this technology, turning the theory into a practical air defence system. Between 1953 and 1971, the spit was occupied by the Atomic Weapons Research Establishment. Its primary task was environmental testing to simulate the conditions that nuclear weapons and their components might experience during trials and in service use. Here science and high politics merged, with investigations that were crucial to the credibility of the United Kingdom’s nuclear deterrent forces, the cornerstone of Cold War defence policy. Before a nuclear device is evaluated in trials or a weapon is issued to the services, its design and safety in operational use needs to be rigorously tested. In 1954, a requirement was identified for facilities for the environmental testing of warheads, including vibration and temperature trials. Initially, the need was to test the Mark I atomic bomb, before it was dropped operationally during tests planned for October 1956. For its location, AWRE’s existing trials site at Foulness was considered, but on this already crowded site there was not enough room for the required safety radius of 550 yards (503m) around the proposed test structures. It was also uncertain whether or not the ground at Foulness was strong enough to support the structures. It was in this context that the first test structures were erected at Orford Ness. The first group of facilities were designed by C W Glover and Partners, Consulting Engineers and Architects, London, and their function appears to have been primarily for the environmental testing of devices prior to overseas trials; their cost was £¾ million. Construction commenced after March 1955 and all were complete by July 1958. For access across Stoney Ditch the existing bridge at the northern end of 'The Street' was used and a new concrete road constructed in the direction of the Black Beacon which was chosen as the headquarters area. About 900m to the south west of the existing bridge and close to the First World War barracks a new bridge rated at 5 tons was built across Stony Ditch. On the south side of the ditch the concrete track split into two, one arm headed for Laboratory 2 (currently known as F1) and the other towards the Control Room (currently known as F4). During the late 1950s, AWRE was running a bewildering number of programmes. Based on differing detonation techniques two designs of thermonuclear weapons were proposed ‘Green Bamboo’ and ‘Green Granite’. Two derivatives of the latter ‘Short Granite’ and ‘Purple Granite’ were tested during the ‘Grapple’ series. Work was also proceeding on a device known as the interim weapon; an early design was called ‘Orange Herald’. Such a device, although technically not a thermonuclear weapon, would allow the government to claim that the country had a weapon with a yield in the megaton range, defined as more than 400 kilotons. Later a version codenamed ‘Violet Club’, or ‘Knobkerry’, was issued to the RAF for a short time. AWRE was also developing a smaller tactical weapon that could be carried by a greater variety of aircraft. This was designated ‘Red Beard’ , it measured 12ft (3.66m) in length and weighed 2,000lb (907kg). In June and July 1957 ground vibration trials on a ballistic version of the weapon, attached to a Canberra bomber carrier and fitted with all components and a HE warhead, were carried out at Orford Ness. Consideration was also being given to two even smaller warheads ‘Blue Fox’ and ‘Pixie’ that might be mounted on surface to air missiles. The picture that emerges from the late 1950s is a period of intense activity, where many competing designs were being brought forward for testing, some of which required returning for modifications, while other proceeded to overseas trials. In 1959, it was proposed to expand the environmental test programme to simulate the conditions weapons may encounter when being transported, put in storage and in operational use. To the planners at AWRE the late 1950s marked a high water mark for potential projects, including warheads for the ‘Blue Steel’ stand-off missile, ‘Blue Streak’ intermediate range ballistic missile, ‘Blue Water’ surface to surface missile, the ‘Yellow Sun’ freefall bomb, and the naval Seaslug missile. There was also the prospect of the next generation of weapons represented by the development of WE177 freefall bomb. Britain’s steadily worsening economic situation led to many defence cutbacks, however, including the reduction in overseas garrisons and the ending of national service. In this climate many high-tech defence projects were cancelled and over the next decades the United Kingdom relied on a small number of standard nuclear warhead types. Projects that were carried forward into the 1960s included the Anglicisation of the United States W28 warhead, in British service known as ‘Red Snow’, that was used in the ‘Yellow Sun’ Mk 2 free fall bomb and the ‘Blue Steel’ stand-off missile. In June 1963 it was announced that Britain would proceed with the purchase of the United States, A3T Submarine Launched Ballistic Missile system (Polaris), with AWRE Orford Ness developing the missile’s warhead. Work also continued on the WE177 family of freefall bombs. If success in weapons design is judged by longevity in service it might be regarded as one of the United Kingdom’s most successful projects. The series remained in service use from 1966 to 1998. The operational requirement for this weapon was established in the late 1950s to provide a tactical weapon to replace the Red Beard bomb and that was small enough to be carried by a variety of aircraft. The design was an extremely sophisticated weapon whose yield could be varied and different variants might be dropped in different roles, for example, as a parachute retarded lay down bomb that was designed to hit the ground before detonating, or as a nuclear depth charge. With the introduction of the WE177 and the Polaris system, there was relatively little new work in prospect and in April 1969 the decision was announced to close Orford Ness and to move many of its functions to Aldermaston. The last trial took place on 9 June 1971and the establishment closed on Friday 1 October 1971. On 24 July 1972 Orford Ness formally passed from AWRE to No.2 Explosive Ordnance Disposal Unit of the RAF. In the following decades they worked to clear the range of unexploded munitions and brought other munitions on to the spit for destruction. This work ceased about 1986, although many unexploded munitions still remain on Orford Ness, and some limited work may have carried on here until the early 1990s. Following negotiations with the Ministry of Defence, the National Trust acquired Orford Ness in 1993. Details PRINCIPAL ELEMENTS The scheduled monument includes the monumentalised, standing remains of test buildings on the Orford Ness spit associated with AWRE environmental testing of nuclear devices during two key phases of activity. Some of the structures have shingle bunds around them, which are part of their design, but there are no buried archaeological deposits associated with these structures. The first distinct phase of AWRE activity saw the construction of highly specialised and distinctive testing buildings (Laboratories 1 to 3, and the control room to Laboratory 1), which undertook the pioneering development work for the successful production of Britain’s own nuclear capability known as Blue Danube. During the second phase of activity, from 1959, AWRE Orford Ness concentrated particularly on the development of the WE177 series of freefall bombs and the ET317 warhead for the first generation of Polaris missiles. To test these warheads distinctive and unique structures, the Vibration Test Buildings (National Trust buildings E2 and E3), latterly termed the ‘pagodas’ for their architectural distinctiveness, were constructed in late 1960. It has been suggested that these buildings were designed originally to test 'Blue Streak'. Associated with them is the control room, the magazine and hard impact facility which are contemporary and functionally inter-related. DESCRIPTION The AWRE phase I buildings comprise three testing laboratories (nos. 1 to 3) grouped together in the near centre of the spit, and the Control Room (National Trust building F4) for Laboratory 1. Laboratory 1 (National Trust building F3) was built by 1956 for use as the Large Vibration Laboratory. It is a massive reinforced concrete structure with a large central bay measuring 30.69m (100ft) by 9.13m (30ft) and was designed to mitigate against the effects of an accidental explosion. Its concrete walls were given extra mass by the shingle traverse placed around them, which would tend to force blast vertically rather than laterally. The roof was also relatively weak structure comprising nine steel W-shaped trusses and clad in aluminium sheeting, insulated with cork and covered in felt sheeting. The interior comprises a main bay separated into two unequal portions by a concrete dividing wall, and running along its northern side is a pit 3.18m (5ft 5in) wide and 2.74m (9ft) deep. On the dividing wall are traces of a screen mechanism to ensure that activities either side of the divide remained confidential. The larger Vibration Laboratory to the south east measures 17.32m (57ft) and the smaller Drop Test Laboratory to the north west 12.15m (40ft). Each of the bays was served by its own entrance with wooden entrance doors to either end, creating air locks measuring 10.1m (33ft) and 9.2m (30ft). Although the original specification only called for the testing of the bomb’s central section, the air locks were long enough to accommodate a fully assembled Blue Danube and its carrying trolley. Although manoeuvring such a large item through the south west entrance and into the Drop Test bay would have been extremely tight. A ledge on the top of the longitudinal walls of the central bay marks the position of a travelling crane that was used to position the bomb on the test equipment. Each of the entrance passages was later protected by crude steel doors fashioned from welded reinforcing rods, which may date to the post-AWRE era. Attached to the wall of the main bay are many small bore pipes that carried various services, including electric wires, hydraulic fluids, and carbon dioxide fire suppressant, and within the roof structure are the remains of large air conditioning ducts. On the northern side of the south eastern entrance passage are two rooms that probably accommodated switch and monitoring equipment, and on the south side of the south west entrance passage was a staff room and toilet cubicles. Testing required the building to be temperature and humidity controlled and on the north west side of the mound is a large self-contained reinforced concrete, two bay plant room measuring 21m (69ft) by 3.89m (12ft 8in). This sits within the main shingle traverse and is insulated from it by a surrounding brick wall that acts a damp course. Air conditioning ducts from the main chamber enter this building and surviving plant within indicates that it housed air conditioning plant. On the north side of the traverse is a similar self-contained structure, surviving fittings shows that it mainly housed electrical switch gear, controls for the vibrating machines and carbon dioxide supplies for the fire suppressant system. The operations within Laboratory 1 were considered to be so hazardous that it was provided with a detached Control Room (National Trust building F4) 130m (142yds) to its north east. This is an L-shaped reinforced concrete structure, originally with an open sided porch on its north east side that gave access to the control and monitoring room to the south west. This comprised two elements; a taller section to the north east that housed air conditioning plant, some of which survives, an entrance passage; toilet cubicles and to its southwest a large open room with a suspended floor that housed the monitoring equipment, of which a few metal cabinets survive. To protect the building from any accidental explosions in Laboratory 1 its south west side was protected by a shingle mound. In late 1963, or early 1964, the Control Room was modified to serve the new Impact Facility (National Trust building F5 - see below) that was being constructed to its north east. Alterations to the Control Room included the bricking up of the open porch and the insertion of double doors protected by a small projecting brick porch. Laboratory 2 (National Trust building F1) was the third structure of this group to be erected, built between 1955 and 1958. Originally built to test Blue Danube casings, the Laboratory was probably modified in 1962 when a large Napier centrifuge on a brick housing was constructed. The laboratory is constructed from reinforced concrete with a large central bay 30.67m (99ft 9in) by 9.05m (29ft 9in) oriented roughly east to west. To increase the available height in the chamber, its A-frame, angle iron roof trusses are raised 0.6m (2ft) above the tops of the walls. The roof was originally clad with cork insulation board covered in aluminium sheets and protected by an outer asphalt coat. The main entrance to the central bay was from the east where a T-shaped road layout provided enough space for a vehicle and trailer to reverse into the building. The concrete entry porch was originally closed by wooden doors, but in common with the other earlier laboratories it was later secured by crude steel doors with an electrical alarm or catch. In common with Laboratory 1 the distance between the wooden doors would have probably been large enough to accommodate a fully assembled Blue Danube casing and its trolley. The building is also entered from the west through another large entrance, also with an entrance passage secured by double wooden doors, and later crude steel gates. Internally, there are two staff amenity rooms adjacent to the west entrance. Entry from this aisle into the main chamber was through two openings in the main side wall, which would have restricted the size of items that could be taken through. At the western end of the building is a large reinforced concrete plant room, which is divided into two bays; the north bay housed a small control room and the southern, a large air conditioning plant. Surviving drawings indicate that the plant room was modified in 1963, alterations include the insertion of a single door to give access to the control room and the addition of a brick outshot to house a transformer and rectifier. At the northern end of the chamber was a Napier centrifuge, this was housed in a ground level, circular brick built feature 30ft (9.144m) in diameter, which could be entered by doorways to the east and west. The centrifuge was supported on a central base plate and above two rolled steel joists to the north and south, which have subsequently been cut off for scrap, leaving only their end sections embedded in the side walls. The centrifuge arm was 16ft (4.88m) in diameter, was capable of supporting a test piece weighing up to 1,000 lbs (453.6 kg), and was rated at 100,000 ‘g’ lb. In the south bay adjacent to the centrifuge is a large red concrete mounting block that probably held some of the control equipment for the centrifuge. A number of features and documentary sources suggest that the centrifuge is a secondary feature. In contrast to the remainder of the structure the circular feature surrounding the centrifuge was brick built rather than concrete. Entrances to either end are also large enough to accommodate a large trailer and potentially a full size Blue Danube casing. Within the main chamber the working area to the east of the centrifuge also appears disproportionately large. Within the roof structure was an internal catwalk to give access to the lighting and large central cork clad, metal air conditioning duct. Internally, along the tops of the walls are projecting ledges that supported the rails for an overhead crane. This might be used to manoeuvre test pieces within the building, and for the installation and maintenance of the centrifuge (see below). To the north and south of the main chamber are side aisles running the full length of the central chamber. These too have concrete walls but are roofed with horizontal beams with curved breeze blocks between them; above they are covered by the shingle mound. Each of the side aisles had an emergency escape exit, both also later secured by crude steel doors. At the western end of the central bay is a raised control room, accessed from a flight of concrete steps on the north wall. Laboratory 3 (National Trust building F2) built between 1955 and 1958, was the climatic testing lab comprising two elements, the laboratory itself and the Condense Pump House to the east. Its function was to either warm or chill a weapon to simulate the variations of temperature that it might face in service. It is constructed from reinforced concrete with a barrel vaulted roof and entered from its south side through a concrete canopy, and whose southern wall was revetted with shingle. To manoeuvre the heavy test objects into position there was a hoist mounted on a beam secured to the underside of the canopy and roof of the main chamber, traces of its fittings may still be seen. Entry into the chamber was originally through double wooden doors, in common with the other earlier Laboratories security was strengthened by the addition of crude welded steel doors with may be post-AWRE features. At the top of these doors is a slot for the overhead lifting beam indicating that the doors were added while the building was operational. The interior comprises a large central chamber, 24.50m (80ft 5ins) by 6.0m (19ft 6in), and is divided into two sections. To the south was the preparation area and on its walls are the remains of electric conduits and small bore pipes for electric cabling. To the north was a rear insulated chamber 13.5m (44ft 4in) in length, which was separated from the preparation area by a cement covered expandomesh wall and a metal clad sliding door carried on an overhead rail. This slid into a corridor to the west that also gives access to a small switch room. The working area of the rear chamber measured 9.14m (30ft) by 3m (10ft) by 3m (10ft) and its floor set on four dwarf concrete walls was capable of supporting 6 tons. The temperature range that could be achieved varied between plus 60° to minus 60° centigrade, and humidity 20° on either side of the ambient, while undergoing thermal tests an object might also be subject to vibration. Further to the west on the spit are the buildings of the second phase. The most distinctive structures built during this phase were the two Vibration Test Buildings, now commonly referred to as ‘The Pagodas’ (National Trust buildings E2 and E3). The specification for the Vibration Test Buildings included the ability to withstand the accidental detonation of 400lbs (181.4kg) of high explosives; they were designed by G W Dixon ARIBA for the UK Atomic Energy Authority and are identical. Both Vibration Test Buildings, their control room and centrifuge were constructed in 1960. They comprise a large reinforced concrete central cell 16.47m (54ft) by 7.30m (24ft) covered by a massive reinforced concrete roof supported on sixteen reinforced concrete columns. To the south and east of the main chambers are self-contained plant rooms. The main access to the building is from the south through an entrance passage which was originally sealed by a pair of outward opening metal covered wooden doors. On its western side, adjacent to the main entrance passage is a blocked doorway that led to a small staff room and toilet. Inside the buildings on the eastern side of the passageway one set of stairs gives access down to the main test cell and another to a walkway around the top of the chamber. At the end of the passageway is a lift pit, which allowed test pieces to be lowered on to the floor of the main test cell. To assist in manoeuvring heavy objects there are a number of substantial steel eyelets screwed into the underside of the roof. A travelling crane also ran on rails mounted on a ledge beneath the windows, a loose plate on the floor recorded ‘Becker twin Lift Maximum Working Load 40 tons serial A-2647-2’. The floor of the main cell is formed of parallel and narrowly spaced steel ‘I’ section beams for test rigs to be firmly secured to the structure. To either side are cable ducts. At the same time as being vibrated objects might also be placed in jackets to simulate extremes of heat and cold, or in a portable altitude chamber to mimic the effects of altitudinal changes. Set into the north wall are seven steel plates with vertical cruciform slots that were also used for securing tests rigs or monitoring equipment. Below these are eight pipes opening from the service passageway to the north. In the south wall are three steel plates with horizontal slots, above the plate is stencilled 1-27ft and below it 1-7.5m. The walkway around three sides of the cell was originally protected by a handrail and there is another handrail fixed to the main wall. Running around the wall is a cable conduit and attached to the wall are various pipes for carrying electrical wires, switches, junction boxes and pressure gauges. Signs on the wall above the lift pit record ‘Telephone Instrument Room’, ‘Vac Pump Running, Vac Pump Stopped’ with associated light fittings. At the north east corner of the cell is a doorway to the rear service passage running east to west along the north side of the building. To the east a flight of stairs gives access to the eastern plant room. To the west another set of stairs provides access to the northern side of the lift pit, the upper walkway and to an emergency escape passage through the north side of the traverse. To the south of the main cell are free-standing Burwell brick-built plant rooms. The main plant room is entered through two sets of double doors on its south side, internally are four machinery mounting plinths. Attached to its west wall is a metal cabinet that probably housed equipment to operate the hydraulic compressor for the internal lift. At the eastern end of the building is a store room with a blocked doorway to the south. The Control Room (National Trust building E4) was constructed for the remote operation and monitoring of the Vibration Test Buildings. It is constructed in a simple, functional and contemporary style in Burwell white bricks that contrast with red asphalt covered lower sections of the metal framed panels of the bays. It is divided into two sections; to the west the slightly taller portion housed control and monitoring equipment, and to the east were staff facilities. The building is entered at the eastern end through an inset covered porch, which is surfaced in red and yellow flag stones arranged in a chequer board design. Entry into the Control Room was past the messengers’ room, located on the west side of the entrance and to its rear a windowless switch room. On the opposite side of the entrance was the cloak room. Along the rear wall is a ladies lavatory, cleaners’ room and a gents’ locker room and lavatory. At the eastern end of the corridor is a small tea room and to its south a large mess room. The taller western section of the building is split into two by a longitudinal east to west corridor. At its eastern end to the south is a store room and on the opposite side of the corridor a dark room. To their west and to either side were six almost identical bays, although the two in the south west corner are open to form a single large room. These rooms were used for housing control and monitoring equipment, which was supported on a raised floor, the under floor void probably accommodated air conditioning pipes and cabling. To reduce noise the upper sections of these rooms and their ceilings are lined with square pierced plaster board panels. The centrifuge building (National Trust building E 1) lies just to the west of the Vibration Test buildings and is a rectangular concrete structure with gable ends to the north and south. It was originally entered from the west through 2 doorways which have subsequently been sealed with breeze blocks. In the southern opening a steel cage door has recently been inserted. Immediately to the north of the door opening is a small square opening to the washroom. At eaves height on the west wall are two metal ventilation grills, also on this wall are various small bore electrical pipes. The north gable is blank apart form a small square opening. The north and east sides of the building are protected by a shingle traverse supported by concrete wing walls on the north-west and south-east corners. The building is covered by a gently pitched roof supported on three RSJ girders with angle iron purlins supporting insulation boards and the pressed metal outer cladding. The interior of the centrifuge was lit by sealed fluorescent units and heated by radiators on all walls. In the centre of the building is the circular brick-lined centrifuge pit with a diameter of c.8m and depth of c.2.5m. In the centre of the pits the central mounting plate for the centrifuge with a cable duct leading to the north east corner and a lower self contained equipment room. To the south west, north east and south east the pits’ brick wall is interrupted by a concrete section, above which may mark the position of the framework to support the centrifuge and its turning gear. To the south a set of concrete stairs provides access into the pit. It is finished in green paint, the remainder of the interior is yellow. A ledge running at eaves height along the east and west walls formerly supported an overhead travelling crane. At the north end of the building are two self contained instrumentation rooms and a door in the east wall that gave access to the emergency escape passage and the pressed metal outer cladding. Located approximately 800m to the east of the Vibration Test Buildings, the Hard Impact Facility (National Trust building F5) was built by late 1962, in which a weapon, minus its fissile core, was propelled by a rocket powered sled against a concrete wall. It comprises a reinforced concrete wall orientated south east to north west with a battered rear to the south west; this side also has an extended tank at its base now infilled with shingle. On the top of this wall are the remains of the steel and timber superstructure which housed cameras to record the impact of the rocket sledge at the base of the wall, these remains project about 1.7m above the concrete base. On the rear wall there are also the remains of steel mountings that are probably associated with the steel and timber superstructure. At the south west end of the wall are the remains of electrical fittings and a small square bronze fitting. On the north east face of the wall are a number of spalled areas that represent where the bombs impacted on the wall. To the north east a large expanse of cast concrete slab extends away from the wall. On this slab are two electrical switch boxes and a number of metal grid covers that gave access to the cable ducts. The last building for this phase of AWRE activity included in the scheduling is the magazine (National Trust building E5) constructed to store munitions. It was built in 1962, 400m to the north of the Vibration Test Buildings, near to Stoney Ditch. This is a reinforced concrete structure with a barrel vaulted roof and is revetted on all sides by shingle traverses. The interior comprises a main drive through entrance passage aligned roughly north to south and surfaced in a smooth concrete surface. To either end it was closed by wooden doors that were set back from ends of the passageway. These comprised a set of double doors and a single pedestrian entrance to one side. At eaves height above the passage way are a series of mounting plates that supported an overhead monorail. On the western side of the passage are two self-contained storage magazines, each of which was formerly closed by outward opening wooden doors. At the entrance to each of the rooms wooden batons on the walls indicate the presence of toeboards, separating a clean magazine area from a dirty outer area. The two bays differ slightly in size, the south bays measures 7.45m (24ft 6ins) by 4.55m (15ft), and the north bay measures 9.15m (30ft) by 7.45m (24ft 6in), both are 5.12m (16ft) high. Each was ventilated through a roof vent with a tall vertical stack projecting through the roof, and by a pair of vents leading into a rear air conditioning plant room, which was entered through a single door to the south. EXTENT OF SCHEDULING The scheduled monument comprises 10 separate areas of protection, restricted to the following buildings and, where present, their protective bunds: Laboratories 1 to 3, and the control room to Laboratory 1, the two vibration test buildings and their centrifuge and control room, the magazine to the north and hard impact facility to the east. Excluded are all concrete roads, paths and associated street furniture, posts and fences on Orford Beach, including modern posts and signage erected by the National Trust.