R4 ROTOR Sector Operations Command headquarters, Drum Brae/Gyle, Edinburgh

Description

The Barnton quarry military complex is located in the west of Edinburgh and was built in two distinct phases, the first during the Second World War and the second in 1951-53. The two buildings comprise a Second World War-era Sector Operations Command centre and a Cold War-era R4 ROTOR radar system headquarters, built within two former quarries on the north side of Corstorphine Hill, Edinburgh and are connected by a tunnel.

The early 1940s buildings on the site are the southernmost elements of the group. These are the Sector Operations Command (SOC) centre with an associated ancillary building, likely a power supply building for the site. The buildings were built within the disused Barnton Mount Quarry and are made of brick and reinforced concrete with flat concrete roofs. There are minimal openings in the exterior walls, including simple door openings with concrete lintels, with only a few windows openings, mostly to the southwest corner where the building connects to the tunnel into the later R4 building. The tunnel is constructed of cast iron segments designed for use on the London Underground. Some of the windows are covered by steel shutters, while others have been sealed.

The interior layouts of the early 1940s buildings are functional, with the main SOC building being designed around a large central plotting room standing the full two-storey height of the building. There are surrounding office and ancillary rooms on three sides of the plotting room at both ground and first floor level, with a balcony at first floor level also extending around the same sides. There are further rooms to the north, west and south of the plotting room and a central corridor runs north-south through the length of the structure. Most of the interior features have been lost, although some historic elements do remain. These include electrical fixtures and wiring, stair balustrades, doors and much of the paintwork, including painted signage.

The second phase of construction dating to 1951-53 is to the north of the group and comprises a three-storey subterranean R4 ROTOR Sector Operations Centre, the headquarters for the Caledonian Sector of the ROTOR radar system. The building is built within the Barnton Quarry using the 'Cut and Cover' technique, in which a structure is built within an excavated hole that was then buried to create a subterranean space, although in the case of Barnton the quarry itself provided the initial excavation. The hole is lined with a gravel base onto which a reinforced concrete slab was laid. There is a second concrete floor layer laid over a waterproof membrane. The walls of the structure are of reinforced concrete up to three metres thick and waterproofed with bitumen paint. The roof of the overall structure is constructed of concrete cast in steel troughs, with the entire structure then buried under soil. Internally, the walls are constructed of brick and timber, with some timber boarding and cork linings remaining. Surviving internal features include major plant machinery on the lowest level, the cast iron balustrades on the main stairwell, the ventilation ducting and wiring and electrical fixtures and fittings. Interior features such as two of the six main blast doors and most of the telecommunications equipment have been removed from the site in the period since it was decommissioned.

In accordance with Section 1 (4A) of the Planning (Listed Buildings and Conservation Areas) (Scotland) Act 1997 the following are excluded from the listing: The ancillary power supply and standby set building to the south.

The ancillary building to the south of the main structures is a Second World War power supply building, with a later extension built around 1961 to house the standby set of generator equipment for the facility. The power supply building is part of a common building type, built on a wide range of Second World War sites to a standard pattern, and as a result it is of no significant interest in listing terms. The extension to house the standby set was built to replace an earlier remote standby set house at Barnton Grove and is also not of significant interest in listing terms.

Historical development

The complex of military buildings at Barnton Quarry were built within a 20-year period encompassing the Second World War and the early Cold War. The first phase of construction was the Sector Operations Command centre. This was developed as a replacement for an existing SOC at RAF Turnhouse (now Edinburgh Airport) as part of strategic change to move operational command centres away from sites on the airfields they served. This dispersed arrangement was seen as less vulnerable to attack, as an attack on the airfield would not disrupt the operations of the SOC. Operations centres of this type were built across Britain as part of the war effort, and other surviving examples can be seen at Leuchars (LB51422), Tain (LB44945) and Boyndie (LB49836).

Following the end of the Second World War and the transition into the early years of the Cold War, the needs of aerial defence also changed. The main danger in the late 1940s was identified as long-range Soviet bombers such as the Tupolev Tu-4, particularly following the Soviet's successful testing of nuclear bombs in 1949. As the British radar capabilities had been reduced following the end of the Second World War, it was insufficient for early warning purposes in the advent of a Soviet attack. As a result, in 1950 development began on a new radar network, codenamed ROTOR.

The ROTOR system made use of a combination of upgraded Second World War radar sites and purpose-built new structures. The system was designed around six air defence sectors, each covering an area of Britain. Within each sector was a mix of Centimetric Early Warning, Chain Home, and Chain Home Extra Low radar sites, providing a broad spectrum of detection. The radar sites would then relay relevant information to the Sector Operations Centre of their sector, where the information would be collated and orders relayed to the Ground Control Intercept stations within the sector, who would then alert the relevant fighter airfields under their control.

Barnton Quarry was selected as the location for the construction of the Sector Operations Centre for the Scottish Sector, designated R4 along with the other SOC sites. Building work began in 1951, with most of the construction work completed by the end of 1952, although delays in the supply of telecommunications equipment meant the site was not operational until February 1953.

Even during Barnton's construction, the long-term viability of the ROTOR system was being identified as limited due to rapid advances in technology. These included the development of the Type 80 radar system, although at first this was seen to improve the effectiveness of the ROTOR network, and the development of faster long-range strategic bombers such as the Tupolev Tu-95. These advancements rendered the original design of the ROTOR system officially obsolete by 1956, as it had insufficient range and response time to effectively counter the speed and destructive power now available to the Soviet Union.

Barnton continued in use as the Air Defence Notification Centre North until October 1958, at which time it was downgraded to Care and Maintenance status. It was subsequently transferred to the Scottish Office and refitted internally to serve as the Scottish Central Emergency Government Headquarters, one of fourteen Regional Seats of Government within Britain, part of the civil defence network intended to provide shelter for a regional commissioner to maintain some level of command and control over the relevant area in the event of the central government's destruction during a nuclear attack. It continued in this role until full closure in 1983 and in 1984 was transferred to Lothian Regional Council. While in the council's ownership they considered the site for potential use as an emergency centre, although in the end this did not happen due to a lack of funding for the proposal. In 1987 it was sold into private ownership and fell into dereliction, with fires in 1991 and 1993 damaging the interior of the structure. Since 2011, there has been a planned restoration programme, seeking to restore the bunker to its 1952 layout and open the site as a visitor attraction.

Statement of Interest

The Barnton Quarry Sector Operations Command centre and R4 ROTOR Sector Operations Centre meet(s) the criteria of special architectural or historic interest for the following reasons:

The design and engineering of the buildings are directly related to their functions, and this remains recognisable today. The Second World War Sector Operations Command centre follows a standard design pattern for a building of this type, as does the R4 building, but the adaptation of the R4 design to reflect the specific needs of the Barnton site, such as the connecting tunnel.

The buildings are a well-preserved physical reminder of two of the major global periods of conflict that helped define the 20^th century, and in both cases many of their contemporary related structures have been either heavily altered or demolished, further adding to the significance of these surviving examples.

The R4 ROTOR building is an extremely rare example of an early Cold War ROTOR radar headquarters and is the only example where the original layout is visible due to the removal of later alterations.

The surviving two phases of the site directly illustrate of the adoption and development of radar early warning systems as part of aerial defence networks that began around the Second World War.

Its physical connection to and reuse of a previous Second World War Sector Operations Command Centre is unique amongst the purpose-built R4 SOC buildings.

The redevelopment and reuse of the site for different roles as the Cold War progressed reflects the changing nature of the conflict as it progressed and the close association of the site to this nationally important period of history.

Design

The design of the Barnton Quarry buildings is highly functional, reflecting their military status. Externally, the design of the Second World War buildings is plain, with no decorative features and minimal openings, reflecting the need for protection against attack over aesthetic or architectural interests. With the additional strength and camouflaging provided by the burial of the R4 building, almost none of the exterior can even be seen today, and those elements that can be, primarily the rear in the vicinity of the secondary access, are similarly plain and functional. The Second World War SOC has been designed in line with a standard War Office template for the building type, while the R4 Rotor bunker has been created to a design by Mott, Hay and Anderson, a London based civil engineering firm who were also involved in the construction of the Forth Road Bridge.

Internally, the design is again functional but of significant interest as the internal plan form has been focussed on maximising the building's efficiency for its intended purpose, in both cases the tracking, plotting and interception of enemy aircraft. As a result of this functional design in both the Second World War and the ROTOR SOC, the primary internal room in each building is the multi-storey plotting well. This room is two storeys high within the earlier building and three storeys within the later example. Within this room would have been located the main mapping and tracking equipment to locate and follow aircraft within the sector being covered. Surrounding this well on three sides are additional rooms in both buildings. On the first floor overlooking the plotting room in the Second World War SOC and at both the first and second floor level, these rooms formerly contained offices that formerly had large windows to allow a clear view of the information being processed below. In this way, additional personnel could clearly see the information on the plotting systems, but without physically obstructing the work of those on the ground floor. From these rooms, orders and information could then be relayed as needed by telephone, telex connections etc.

In order to support the primary functions of the buildings, additional rooms and facilities were provided in ancillary rooms away from the main plotting well. These include the necessary communications connections and facilities to coordinate with other elements of the R4 network within the Scottish sector: the R4 building has a substantial dedicated GPO communications room to house the required systems, located on the ground floor. Adjacent to this, a small radio studio survives within the building near to the base of the plotting well. This was added to the R4 in its later guise as a Regional Seat of Government and would have provided a space for the BBC to continue broadcasting information to the public in the event of a nuclear attack.

The buildings have undergone some alteration since their construction. This includes both intentional changes for operational reasons during the active service of the site and further changes following the decommissioning, including the removal of equipment and the loss of fabric during the fires. In spite of this, the fundamental character of the buildings remains, both in the surviving building layout that reflects the original functions of the building and in the surviving interior features such as the ventilation and communications equipment that were integral parts of its operation.

Setting

The Barnton Quarry complex is located around 4 miles west of Edinburgh city centre, on the northern side of Corstorphine Hill. Despite the location on a hillside, the setting of both the Second World War and Cold War buildings is intentionally discrete, with their construction within disused quarries leading to the structures sitting below the surrounding ground level and thus obscured from view, further shielded by the extensive woodland cover over Corstorphine Hill. This restricted setting aided in the secrecy and camouflage of both phases of the site's use, as they cannot be seen from either Queensferry Road or Clermiston Road, the main thoroughfares passing near to the site. In practice, to an observer on the ground the buildings are only clearly visible from within and immediately around the former quarries. As secrecy and discretion were vital elements of the function of the Barnton Quarry complex, the retention of this restricted and hidden setting is of interest in listing terms.

Although the immediate setting of the buildings uses the disused quarries to provide discretion, the wider setting of the ROTOR building is unusual as it is the only one of the six ROTOR headquarters sites located within an urban setting, with the other examples all found in rural locations. At the time of construction starting in the 1950s the Barnton Quarry site was on the very edge of Edinburgh, with the adjacent developments of Davidson's Mains and Blackhall in place to the east. To the west, the adjacent housing estate at Clermiston is roughly contemporary with the R4 building, constructed between the mid to late 1950s, and so the location of the building within a more urban location than the other examples was possibly intentional. Nevertheless, the use of the existing quarry excavation will have been chosen to save on time and cost.

Although there are no other directly comparable buildings to the Barnton Quarry complex within Scotland, there are still some surviving contemporary sites relating to the Second World War and Cold War in and around Edinburgh, reflecting the strategic importance of the Firth of Forth and the surrounding towns and cities, along with strategically valuable sites like the Rosyth Naval Base, the Forth Bridge and the industries around Falkirk and Grangemouth.

The development of RAF Turnhouse into Edinburgh Airport has removed almost all traces of the Second World War airfield, but other contemporary buildings nearby to Barnton include an Air Raid Precautions Report Centre (LB52496) in Roseburn Park and an anti-aircraft battery at Liberton (SM13607), along with the substantial multi-period defensive works on some of the Forth islands, including Inchcolm (SM90166) and Inchkeith (SM3838).

Other surviving elements of the Scottish Sector ROTOR network that would formerly have reported to Barnton include the former R3 Ground Control Intercept radar station at Anstruther, now a museum, along with surviving elements at other sites across Scotland including Saxa Vord on Shetland, and Buchan and Inverbervie in Aberdeenshire. The 1950s anti-aircraft operations rooms at Craigiehall in Edinburgh (LB52396) and Torrance House in East Kilbride were also linked to the ROTOR network as they would have received information from Barnton and relayed this in turn to the relevant anti-air defence sites. During its later use as a Regional Seat of Government, Barnton also had connections to other sites in the civil defence network, including the former Regional War Rooms at East Kilbride (SM11068) and Kirknewton, now demolished.

Age and rarity

Although the Barnton Quarry complex is of relatively recent age, the buildings within are reflective of the periods of conflict during which they were constructed and used, specifically the Second World War and the Cold War. Throughout the 20^th century, the rapidly changing dangers presented by aerial warfare required continual development and adaptation of strategic and tactical responses, as can be seen in the multiple variations of use in the complex, from the original fighter operations centre through to its final role as a civil defence bunker.

In terms of rarity, the complex is unique in several ways. Although other examples of Second World War fighter operations centres are still extant, including other listed examples at Leuchars (LB51422), Tain (LB44945) and Boyndie (LB49836), the total number has significantly reduced since the end of the war as many have been demolished or heavily altered. In contrast to other surviving examples, the site at Barnton is the only example which is directly linked to one of its successors in the form of a ROTOR Sector Operations Centre, and the similarity of design, particularly in the grouping of rooms around a central "well" for the tracking and plotting of aircraft can be easily seen.

Barnton Quarry was the only R4 SOC created within Scotland, with three other purpose-built examples at Kelvedon Hatch in Essex, Bawburgh in Norfolk and Shipton in Yorkshire and two further examples utilising existing buildings at Box in Wiltshire and Longley Lane in Lancashire. All four of the purpose-built R4 structures survive, which is not surprising given the scale and strength of their construction. Kelvedon Hatch is preserved as a visitor attraction, with the interior retained largely as it was at decommissioning in 1993. Both Bawburgh and Shipton are in private ownership, and no interior features are believed to survive. Finally, and in part because the post-closure damage to the site has led to the removal of later alterations and additions, Barnton is the only one of the purpose-built R4 bunkers where the original ROTOR SOC layout survives largely intact.

Social historical interest

The initial use of this site as a Sector Operations Centre in the later years of the Second World War reflects changing strategic approaches to aerial warfare, and the building is wholly designed around its function, with minimal decorative or aesthetic features.

The selection and use of the site as a Sector Operations Centre for the ROTOR system in the 1950s makes the buildings an integral part of British plans for radar detection and ground control interception systems in the early years of the Cold War.

Although the ROTOR system was obsolete by the end of the 1950s, the refit and reuse of the structure for civil defence purposes until the 1980s reflected the continuing value of this site. From the beginning of construction on site in 1952, through its active use as a ROTOR SOC and a Regional Seat of Government, until the final decommissioning and transfer of the property to Lothian Regional Council in 1984, the former R4 building at Barnton was an active part of Britain's planning and defence for 32 years of the roughly 44 year Cold War era.

The building is a tangible link to both the scale of the global geopolitical stand-off, and the levels of secrecy, subterfuge and fear that were among its defining characteristics.

Association with people or events of national importance

The Barnton Quarry complex is directly connected to two of the most important and defining events of the 20^th century, namely the Second World War and the Cold War. Although a replacement for the original wartime Sector Operations Centre on the airfield at RAF Turnhouse (now Edinburgh Airport), it served an active role in the conflict and is one of the few surviving buildings relating to the operations of RAF Turnhouse, as most other wartime buildings have been removed as the airport has developed over time. The subsequent Cold War use of the site, initially in a continuing aerial defence role and subsequently for civil defence, both operating at a strategic control level covering the whole of Scotland, makes Barnton Quarry an extremely rare survival within Scotland of a purpose built, strategically significant site, constructed and operational during two of the defining periods of conflict of the 20^th century.

External Links

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