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Visit report – RAF Saxa Vord

In 1945, the Allies had narrowly won the Second World War but soon realised that a new and potentially dangerous world power was emerging. In what was to become the Cold War, Great Britain, weakened after the virtual collapse of the Empire, aligned with the United States in a war of attrition against their Second World War ally the Soviet Union. This was politically an incredibly complicated era, but one that Britain found herself geographically and politically relatively isolated, and still greatly wounded after the huge social and financial sacrifices of the war, albeit as a wounded victor. As this hard-fought victory was coming into sight, the War Department slowly started to decommission the Luftwaffe beating network of Chain Home (CH) and Ground Controlled Intercept (GCI) direction-finding stations1Later called RADAR, a term coined in 1940 by the US Navy, an acronym of Radio Detection and Ranging constructed in haste only a few years before. There was a moderate period of realignment before the realisation that the country was now behind and had some technological catching up to do to remain safe.

Of the 170 radar stations decommissioned or retained at the end of the Second World War, 66 were selected for retention and upgrade. This massive programme of works was given the codename ROTOR. To chart the ROTOR programme is to chart technical capability development during the Cold War; something I could not hope to do in this article. To give some context to the ROTOR station at Saxa Vord, it helps to lay down some background to the development of ROTOR.

  • ROTOR 1 (1952 – 1954) saw the upgrade of 28 Chain Home stations and the construction of 14 new underground stations
  • ROTOR 2 (1954 – 1958) the construction of 11 new underground Ground Controlled Intercept (GCI) stations and the upgrade of existing sites with the Type 80 radar
  • ROTOR 3 (for completion in 1957) filled in radar coverage gaps to the north and west of the British Isles and to major shipping ports around the country

On 10 December 1952, a group of engineers from the General Post Office (G.P.O.) and Headquarters Fighter Command met in the small hamlet of Balta Sound on the most northern Shetland island of Unst.2Document AIR 2-12064 Rotor 3 RAF Station Saxa Vord held in the National Archives They were discussing the construction of a new radar station. The Second World War Chain Home site at Skaw was found to “be almost dismantled” with generators “of no further use”, new locations had to be found for a technical building, four radar heads (a Stage 1A C.E.W.3Centimetric Early Warning, the term given to the surveillance radar technology deployed early in the Rotor programme and three Type 13), transmit and receive sites for VHF communications, a site for the G.P.O. to operate from, a power station and sufficient domestic site for staff and crew. The site at Saxa Vord would be given the designation AXA and be equipped initially with an above-ground technical building of the new Air Ministry design R.10.

In addition to the work undertaken on the radar station, the Admiralty would have a new two-storey facility constructed, known as the Experimental Building. Interestingly records at the time stated that “for security reasons, all reference to the Admiralty should be omitted.” Their equipment would include a Type 227 radar and a series of seabed sensors.

Construction would be challenging in part due to the remote location but also due to the changeable and extreme weather, but by the end of March 1954 the designs had been agreed and the contract was due to be placed for construction to begin. Holland, Hannen and Cubitts (Scotland) Limited were awarded just over £434,000 to prepare the site and erect the dozens of buildings and services required for the new radar station. The civil engineering challenge of constructing at Saxa Vord can not be underestimated. The island lies at the furthest north point of the British Isles with an economy historically based on fishing. There was effectively no existing civil infrastructure that could support the site. This would result in a new jetty and slipway being constructed, fresh water wells being dug, a sewage treatment plant being constructed as well as new roads, street lighting, housing, diesel generator and power distribution networks. Accommodation, married quarters, recreation facilities, a fire station and a sick bay were also constructed to support the staff and their families posted there. It is challenges like this during construction that often mean these sites aren’t demolished at the end of their life; it would simply prove too costly to do so.

Site Overview

The most northerly everything in the United Kingdom!

A theme among business on Unst is they are the most northerly; hotel, pub, cafe, trig pillar and … radar station.

At the time of my visit, the site had been abandoned for around 17 years. It was apparent that sections had been empty for much longer. Based on the condition of the various buildings, I would estimate that the R.101 was the only building still operational, or at least under care and custody at the time it was eventually closed. The large generator and telephone exchange inside the building would most likely have been the final rooms to cease operation as they would have likely still served the upper site. I paid 3 visits to the site across 2 days taking photographs and video.

This aerial image4Canmore reference 1446649 was taken in 2014 and shows both the upper and lower sites at Saxa Vord. The terrain is difficult to visualise, but the lower site (top of the image) lies around 30m lower in elevation compared to the radar heads on the top site. While the radar site had been decommissioned for a while, it has recently undergone an upgrade to a Remote Radar Head (RRH) and is very much still in operation. The traces and footprints of removed buildings and structures is visible in the aerial photograph, but now a single radome protects the radar head from the extremes of Shetland weather.

The lower technical site I visited on this trip was opened in 1957, closed in 2006 and was sold by the MOD in 2012. This report is based on a visit in 2023, 11 years after the site was transferred into private hands.

R.10 operations block

The operations block designated R.10 was one of the last building designs to be completed during the ROTOR project. When initial visits to siste were being conducted in 1953 the building type was still to be specified, but due to the layout of the ground, it was recognised that an above-ground block would have to be constructed. I imagine the prefix “R” to the drawing number denoted their association with the ROTOR project, but I haven’t seen this confirmed yet.

The R.10 was the first operational building constructed on the site. The entry control point (E.C.P.) is the small projection on the left of the building, and the flat roof is the plan of the single-storey operations block.
The R.10 guardroom and entrance to the south side of the complex. There are several interesting features we can see; A – Based on the official records, we know the building was constructed from 9″ pre-firmed concrete blocks, we can see those visible here. B – These raised areas in front of the windows were to support sandbags that could be filled and placed here in the event the building needed to become defensible. C – This corridor was constructed later and led to the newer R.101 hardened operations block. Both the R.10 and R.101 used the same guard room and access control. D – An air raid siren that could be controlled from the guardroom to warn of attack.

The R.10 fell out of use as an operations block when the upgraded R.101 was constructed and operations transferred in 1979.5http://ahistoryofrafsaxavord.blogspot.com/2011/03/r101-from-outside.html accessed 27 March 2024 The floor of this corridor is raised to allow cables and facilities to run underneath, but after years of neglect it is in a poor condition and it’s only possible to pass by walking along the line of the joists and not in the middle of the panels themselves.

After it became non-operational the building remained in use as offices and store rooms. The main structure remains unchanged but many internal partition walls make it difficult to visualise the original layout.

One of the more interesting relics in the R.10 was the briefing room. The walls are still adorned with RESTRICTED posters and identification posters. The curtains covering the noticeboard were intended to be pulled across when non-cleared visitors were in the room, to visually protect classified information.
The remaining noticeboard at the back of the briefing room showing images of not only Soviet era vessels but NATO ships to aid identification.

This room was the R.10 air conditioning plant room. Due to large equipment being installed, the floor was sunken to accommodate it while keeping the roof level consistent. It appears that when the R.10 fell out of use this room became a gym.

This room is typical of the repurposed R.10 rooms. The rear and left side walls are original, but the wall on the right is a later partition, likely constructed around 1980 when the R.10 was repurposed. The secure cabinet in the rear right of the time would have housed secure network equipment, and the white PVC conduit has been sealed with anti-tamper tape to maintain the integrity of the fibre optic cables running inside.

Photographic projectors

Formally known as a Kelvin Hughes photographic projector or a photographic display unit (P.D.U.), this fascinating automated analogue display system took a photograph of the radar plot from a cathode ray (C.R.) screen, developed it, with the resulting image being displayed on a 5-inch thick glass table 7’7″ square. This system required considerable equipment, which would be set in a well below ground level, with the glass table above in the radar plotting room. While the P.D.U. was deployed across many ROTOR stations, Saxa Vord was the only station with the equipment in the single-storey ground-level R.10 operations block. Given the state of the terrain, this proved to be a challenge, but a P.D.U. well was excavated and is still in situ; easy to miss on any site visit and now covered over, but accessed by a set of wooden stairs.

Admiralty experimental building

It is ironic we know this building as the Admiralty Annex given the specific request to omit all references to the Admiralty. We know from construction notes in the National Archives6AIR 2/12064 what the specification for the original building was. The Admiralty requested a two-storey building (designed for later extension to three) around 50′ x 30′ constructed of 9″ pre-firmed concrete blocks. Double steel casemates were to be used in the windows; it is unclear why this requirement was specified, but it may have been related to security. The ground floor would contain an analysis room, a general office, an office for the Officer in Charge (O.I.C.), a workshop, store, battery room and dark room. Upstairs on the first floor was the instrument room, subdivided with steel and glass partitions. All of this would cost approximately £15,000 in 1954.

Buried away in the National Archives file AIR 2/12064 is a SECRET memo FNM/ALI/CCB.11. containing a single reference to “development of the Corsair station.” The reason behind the secrecy becomes apparent.

An Admiralty Research Laboratory (A.R.L.) programme of work was established under the codename of CORSAIR as an initiative to achieve even greater ranges, perceived as necessary to counter the threat posed by the growing number of Soviet-operated submarines. The CORSAIR programme included study, experiments and development of shore-based, submarine detection methods using low frequency sound, with the initial emphasis on wide-band correlation techniques.

Admiralty Research Laboratory – Passive Sonar research, http://arl-teddington.org.uk/arl_corsair.htm accessed 27 March 2024
The three-storey Admiralty building was originally constructed as a two-storey building It has been clad in corrugated iron sheeting to help protect it from the weather. The windowless extension on the left of the image is an emergency escape staircase that was constructed when the building was handed over from the Admiralty to the Air Ministry. The water in the foreground is the Emergency Water Supply (E.W.S.).

Ground floor

Joined to the R.10 via a corridor, the Admiralty building shared welfare facilities with the Air Ministry, later R.A.F. station. This photograph it ground level shows the entrance to the Admiralty part of the building, with the stairs on the right being the only way for personnel to access the upper floor/s. An equipment hoist was provided, operated from the top floor and used to lift heavy racks and equipment throughout the building.

The ground floor originally contained offices and workshops but has since been converted to include a kitchen and canteen.

A kitchen was constructed on the ground floor of the Admiralty building when the R.A.F. took over the building.
A ground-floor office in the Admiralty building. The original cement block wall reflecting how the R.10 was constructed can be seen on the far wall.

First floor

We know from the records that when this building was first constructed the first floor housed the instrument room and was sub-divided by steel and glass partitions. Although now badly vandalised this floor has been sub-divided later in its life with plasterboard walls.

Second floor

The upper floor of the Admiralty building was added at a late date (unknown). This floor would most likely have been used to house a scaled-up operational system following the initial experiments that had been carried out during project CORSAIR when the building was constructed. The electric chain hoist drops to the ground floor and could have been used to lift heavy equipment to the upper floors. The single original staircase is through the doorway on the left of the picture.

The Annex

According to the History of Sava Vord website7https://ahistoryofrafsaxavord.blogspot.com/search?q=annex the Annex was completed around the same time as the Admiralty building in the mid-1950s. Both buildings have seen repurposing since the Admiralty moved out, so it is hard to establish the original function of the rooms. Most of what remains in these buildings today is from the 1980s.

Ground floor

The Annex is one of the more dilapidated buildings on the site, despite appearing to retain its structural integrity. Much of the paint is peeling off the walls and many of the fixtures and fittings have been removed there is an atmosphere of desolation inside and out.

The room on the ground floor was last used as a workshop, with a double-door entrance and machine positions marked out on the floor and walls. There appear to be offices and storerooms leading off from the main room.

First floor

The desolation of the Annex continues to the first floor. There are some nice details that I have displayed below, in particular, I find the peeling paint compelling.

Damp is the worst enemy of buildings like this. While the fabric of the building seems intact, the concrete is sweating and forcing any paint and fixtures off.

R.101 Operations building

Without being dramatic, this building was the jewel in the crown of the exploration. Having laid empty for nearly 2 decades the state of preservation was remarkable. Damp had started to set in (which is why I think the doors were left open!) and the air was thick and unhealthy. The only one of its type constructed, I felt privileged to have been able to record it. With no windows, or natural or artificial light other than my torch, it was eerily dark and silent. And remarkably for an abandoned building, there were no signs of wildlife in the R101. It is truly a sealed box.

A comparison image showing the construction partly complete in 1978 and the derelict building in 2023.

The huge construction took 3 years to complete and in 1979 operations transferred from the R.10 to the new R.101. After a technical refurbishment in 1984, the building remained in use until the late 1990s.

Entrance and access corridor

The tunnel as it leaves the R.10 before descending two flights of stairs to cross under the road.
The tunnel entrance to the R.101 after passing under the road.
The imposing blast door (open) protects the R.101 from blast, attack and contamination.

Corridor

A 1980s photograph from the History of Saxa Vord blog shows how the operations building had changed through the years. The picture on the right is possible before a refurbishment in 1984, but the colour image to the left shows how it appeared in 2023.

I am unsure what this room below is called, but the image on the right from some time in the 1980s shows an operator at the SSSB console. SSSB was an acronym for Ship-to-Shore Buffer, defined as a “real-time data link buffer system supporting data exchange between naval forces, including airborne assets, and their associated air defence ground environment units.”8Definition of SSSB https://npc.ncia.nato.int/Pages/Ship-Shore-Ship-Buffer-(SSSB).aspx accessed 23 March 2024 I have been able to match the images using the unique tiled walls, blue ceiling as well as the conduit and ventilation outlets.

Radar office and workshop

Backup power set

It is assumed that power to the R.101 and the rest of the site was provided in normal times from either the National Grid or more likely the power station located in the domestic site. However, in the event the site became removed from this grid, it was essential that the station could continue to operate independently. Located within the R.101 building, but outside the main airlock and secure bulkhead doors, was the backup generator. The centrepiece of this generator was a diesel marine engine; a Mirrlees Blackstone ESL6 Mk. 2 likely dating from the early 1980s.

Tempest control

TEMPEST stands for “Telecommunications Electronics Materials Protected from Emanating Spurious Transmissions”. It is a (…) specification for protecting against data theft through the interception of electromagnetic radiation. Computers and other electronic devices emit radio frequency (RF) signals and electromagnetic radiation that cybercriminals can use to reconstruct intelligible data.

TEMPEST was the codename of a U.S. government project in the late 1960s that studied this threat. (…) It includes strict requirements for the electromagnetic shielding of equipment, rooms, or even entire buildings. It also specifies distances between equipment and walls and building pipes and the space between cables carrying classified vs. unclassified information.

https://blog.enconnex.com/what-is-tempest accessed 27 March 2024

There are clear signs in the R.101 that TEMPEST measures were in place, including the appointment of a TEMPEST control officer. The measures are particularly clear in what may have been the radar office. This may not have been the role the room played after the post-1984 refurbishment, but it suggests that at least one room was shielded against electromagnetic leakages in and out of the room.

An electrically conductive knife and comb arrangement around the door to ensure the integrity of the Faraday shielding.
Each phase of the 400v power entering the room was passed through a filter to remove any possible leakage of data or injection of malicious signals.

Communications

Using radios inside a concrete shell won’t work. The relatively weak radiated signals will not have the power to penetrate the fabric of the building, they will also reflect off the many hard surfaces and cause considerable interference. In situations like this, a system called a leaky feeder or radiating cable is used. This cable running throughout the R.101 acts like an extended radio antenna to the base station, and whereas normal coaxial cable is designed to prevent emissions radiating from the cable itself, the leaky feeder had a modified outer conductor which allows signals to be received and radiated from it.

Luckily for us, the cables in the R.101 are marked up as RF cables and they are easily to identify running around the ceiling into almost every room in the bunker.

Defence from ground attack

Being so remote and detached from the inherent security of mainland Great Britain, security must have proven a headache for defence planners at Saxa Vord. If the radar station came under any form of attack or sabotage the existing staff would be responsible for ensuring the continued operation of the early defence radar and protecting the integrity of the other systems operated from the site. There are a series of defensive measures still visible today that hint at some of the methods employed to boost security and I have identified those below.

A concrete block sangar overlooks the approach road to the radar station. The perspex windows can be lowered if the occupants had needed to fire their weapons from the post.
Both upper and lower sites were surrounded by a chain link fence and a ring of powerful floodlights facing out from the compound.
A sangar inside the technical compound. This is smaller than the sangar on the approach road, and had good visibility along the three external facing sides along the perimeter fence.
The raised plinths in front of the windows allowed for sandbags to be pilled up and the building made defensible.
Panic buttons were included inside the R.101 operations building to alert the site of a security situation.
An unloading bay, one of two on the site. These were placed by entrances and aided soldiers to load and unload their weapons safely. An indication live weapons were routinely carried.
A photograph of the newly constructed R.101 operations block shows a sandbag sangar on the roof!9Image from http://ahistoryofrafsaxavord.blogspot.com/2011/03/r101-from-outside.html but marked as (c) MOD accessed 27 March 2024
A Yarnold bunker or sangar on the earth bank surrounding the domestic camp. Providing rudimentary protection from the weather and small arms ammunition, this prefabricated defence was used almost exclusively on R.A.F. camps for defence.

Bonus

And for all of the Trigbaggers out there, here is a photograph of S4825, the most northerly trig pillar in the United Kingdom!

  • 1
    Later called RADAR, a term coined in 1940 by the US Navy, an acronym of Radio Detection and Ranging
  • 2
    Document AIR 2-12064 Rotor 3 RAF Station Saxa Vord held in the National Archives
  • 3
    Centimetric Early Warning, the term given to the surveillance radar technology deployed early in the Rotor programme
  • 4
    Canmore reference 1446649
  • 5
    http://ahistoryofrafsaxavord.blogspot.com/2011/03/r101-from-outside.html accessed 27 March 2024
  • 6
    AIR 2/12064
  • 7
    https://ahistoryofrafsaxavord.blogspot.com/search?q=annex
  • 8
    Definition of SSSB https://npc.ncia.nato.int/Pages/Ship-Shore-Ship-Buffer-(SSSB).aspx accessed 23 March 2024
  • 9
    Image from http://ahistoryofrafsaxavord.blogspot.com/2011/03/r101-from-outside.html but marked as (c) MOD accessed 27 March 2024
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