RAF Daws Hill was, in reality, a United States base for its 60 years or so of active service. From the first months of the USA’s involvement in World War II to the dying days of the Cold War, it served as a secure, subterranean, secret command centre for the US Air Force. If only walls had ears….
The USA entered World War II in December 1941 after the Japanese attack on Pearl Harbour. In anticipation of the entry of the US Air Force into the European Theatre, the RAF sought a location for the headquarters of their Bomber Command. A site close to the existing RAF Bomber Command at Walters Ash (five miles north of High Wycombe) was preferred and on 28 March 1942 the entire site of the Wycombe Abbey Girls School was requisitioned. The school was located on a hillside just to the south of the centre of High Wycombe and two weeks later the site was vacated.
No sooner had the girls left the school than the US Eighth Air Force moved in to make it their European headquarters that became known as Station 101. About ¾ of the way up the hill a new underground headquarters codenamed ‘Pinetree’ was built in only 11 months at a cost of £250,000. The bunker had a floor area of 23,000 sq ft with a 10 ft thick reinforced concrete roof and above that a further 25 feet of soil. The side walls were over 5ft thick and to absorb the shock wave from an explosion the building was surrounded by an inner void and then a further 6 feet of reinforced concrete; in effect it was a bunker within a bunker. The hub of the headquarters was the communications centre with direct links to the 8th Air Force Fighter Squadron (at Bushey Hall), Bomber Group Operations Rooms and the Bomber and Fighter Command HQ. The bunker continued to serve as the command centre for the 8th Air Force Bomber Command until the end of World War II.
By the middle of 1946 most of the Americans had vacated the site and a fence was built between the school and the remaining military camp at the top of the hill, this included the bunker which sat in a peninsula of land in the northwest corner of the camp. At this stage it is understood that the bunker was no longer in use.
Cold War threats
In 1950 it became evident that the US Air Force would need to utilise sites in the UK with the threat of attack from the Soviet Union. The Air Ministry still wanted to retain the overall camp including the bunker but the school refused to sell the land and in December 1950 the school signed a 21 year lease prompted by a request from the US Strategic Air Command (SAC) to reoccupy the wartime command centre for its UK-based 7th Air Division; this was established on the site in May 1952 as the 3929th Air Base Squadron. On 10 September of the same year ‘USAF Site, Wycombe Abbey’ was officially opened as a satellite of the 3911th Air Base Ground Group at RAF West Drayton.
Following a more robust request from the Air Ministry 1954 they purchased the land that was to become RAF Daws Hill from the school however this did not include the land the bunker was situated on and a 56 year lease was signed with the school to retain the bunker site. With the withdrawal of the 7th Air Division from four of its East Anglian bases by 1959 the US Strategic Air Command concentrated in Oxfordshire making High Wycombe the natural choice for their new central headquarters and this took place on the 1 July 1959.
A new construction phase followed with the addition of over 70 new buildings with the station acting as the Strategic Air Command’s UK headquarters during the build up to the Cuban missile crisis with the SAC and Bomber Command acting as one combined unit for all practical purposes.
In 1965 the advent of mid-air refuelling for bombers made the B-47 force redundant and US forces in the UK were drastically reduced. The US government was now able to provide a high level of defence direct from bases in the United States and in June 1965 the 7th Air Division at High Wycombe was deactivated with the base being transferred to the US 3rd Air Force and the United States Air Forces in Europe. The 7563rd Air Base Squadron arrived at Daws Hill as part of the US defence of the London area and remained there until January 1971. By 1969 the bunker was no longer in use and by 1976 it was stripped out and almost empty.
Cruise Missiles arrive in the UK
The big defence spending plans of the Reagan administration in the 1980s called for a USAF Wartime HQ for Europe. In April 1984, the Daws Hill base was occupied by the 7520th Air Base Squadron, under the control of the Third Air Force HQ at RAF Mildenhall. A major refurbishment of the bunker took place, much of the cost being to strengthen the building, to help proof it against nuclear, biological or chemical (NBC) attack. At least $33 million was to be spent on electronic equipment. The contract to rebuild the bunker was awarded to Sir Alfred McAlpine with an expected cost of $13 million.
Between 1986 and 1989 when it became fully operational the bunker was completely rebuilt but not extended in operational area. The main extension was for a new plant room and life support systems including air filtration. Use was made of the previously empty void between the two bunker structures as an equipment room. A decontamination area was added at the main entrance which had remained externally little altered from WWII days and large concrete baffles were placed over the three ventilation shafts.
The two-level gallery and operations room was floored over and rooms full of computer equipment replaced the manual plotters of WWII. The site became USAFE (US Airforce Europe) European Theatre of War HQ. A central programming facility for European based cruise missiles was planned for but never completed due to the sudden phasing out of that system. It is understood that the task was undertaken within the RAF Daws Hill base but that it took place in one of the main base above-ground buildings and never moved into the bunker.
Communications links went to all airfields and operational HQs in USAFE as well as to the Strategic Air Command (SAC) Headquarters bunker at Offut Air Force Base in Nebraska. The main communications hub of USAF in the UK at Croughton (also an international Autodin [data transfer] centre) was also directly linked as was RAF Strike Command Tactical Control Centre at RAF High Wycombe. Another major link connected Permasens in Germany - the Autodin centre for the German Theatre area.
By 1992 there were 225 American military staff and 116 defence department employees working at Daws Hill when the base’s strength was reduced again with the post Cold War rundown in USAFE facilities. The base was deactivated in May 1993 and handed over to the Commander of US Navy Activities UK for use as a vehicle maintenance and warehouse facility. The US Navy had no use for the bunker which was mothballed and retained on care and maintenance. Its only military use in latter years was for US Marine Corps CQB (Close Quarter Battle) and hostage rescue training.
Later in 2012 a prior notification for the demolition of the entire surface features of the bunker had been submitted to the local planning office by the MOD. A number of people raised issues around this and as a result English Heritage got involved and visited and assessed the site. Thankfully sense prevailed and in October 2013 the bunker and its associated surface structures were awarded a Grade II* listing protecting this important historical site from what would have been its inevitable demise.
As well as all the underground features, the protected ventilation towers and the Cold War era decontamination suite were included in the listing. The reasons given are in the adjacent panel. An additional listing (this time at Grade II) was also made to cover the surface generator building, also dating from the Cold War. This unusual feature is only on the surface as the power required within the bunker during its latter years demanded a size of back-up generator that wouldn’t fit within the profile of the original bunker.
Back to School
Following its designation the bunker was handed back to the school. In the period of a few months over the summer of 2013 just before the bunker was handed back to the school the main blast doors to the bunker were locked open. This, coupled with a water leak in the top floor electrical filter room, led to significant damp and mould damage throughout the bunker. This was a source of great frustration to the school as they would prefer to have a bunker with potential re-use rather than a rotting relic.
As soon as the school took back possession of the site and the bunker I visited the site and we located the leak. Shortly afterwards the school maintenance staff fixed the leak and sealed the bunker preventing any further deterioration. Since this time the bunker has dried out significantly and hasn’t deteriorated further but there is still evidence of damage caused during this period. In 2015 the school fitted a new power supply into a room on the top floor of the bunker and is considering fitting out power and dehumidification to the whole of the top floor.
As soon as the bunker was back in School hands, Subterranea Britannica approached the school about arranging a visit for members. In the early days of the handing back of the bunker to the school the structure was broken into numerous times by ‘urban explorers’. In reaction to this the school invested a significant amount of time, effort and money into securing the bunker and deterring future break-ins. After this the school were rather cautious about allowing anyone access to the bunker and we had to work to build a relationship of trust with the school to persuade them to allow us a visit. Following years of back and forth contact with the school the Estates Bursar and the Headmistress finally agreed to a visit for Sub Brit.
Located as it is in the grounds of a prestigious girls’ school, our visit had to be outside term time in the interests of child protection. In order to gain approval for the visit, a method statement was prepared describing the parameters of the visit. The proposal was to have a familiarisation day for six guides who would then host the actual visit. In order to maximise attendance the plan showed six separate tours, each of twelve members – a total of 78 members including the guides. It was a significant milestone for us to be the first group that were allowed a visit so we were keen to agree a number of visitors with the school that we felt would be manageable and at the same time a group size that ensured all attendees could easily see the bunker’s features. We knew that organising the day to show we are competent and reliable would maximise the chances of being able to arrange further visits.
Familiarisation and Rehearsal
On Monday 13 July the guiding team all met up at Daws Hill and were able at last to see the site for ourselves. We had good plans of each level, not as straightforward as it might seem as the bunker is built into the hillside and each floor has a smaller footprint than the one beneath it. To complicate things, one of the plans was printed in the reverse orientation to the other two for some reason which took some time to get our heads round.
We spent some time as a group agreeing the tour route. We were lucky in that the emergency exit would be open and we could operate a ‘through route’ – extremely helpful when we would have over 50 people underground in three separate groups at times. The lead guides took notes of some of the key features and we marked up plans that we would copy and share. We then spent time on the surface agreeing how we would manage car parking, check-in, and any emergencies that we hoped wouldn’t occur. Before the site was locked up for the night, we had chance to retrace the route of the tour again, ensuring as much as possible that it wouldn’t be a case of the blind leading the blind.
D Day Dawns
As the time reached 0930 the first group started arriving and was able to leave a little before 1000, under the guidance of Chris Kenney who as a local resident had driven longingly past the site thousands of times. Each of the guides followed the same general route and pointed out many different features along the way. At this stage our pre-planning was paying off as 20 VIPs were also arriving with Mayoral chains making a strange juxtaposition with boiler suits and hard hats!
Martin Dixon, who was one of the group guides, describes the route that visitors were taken through: “Starting on the surface, the secure compound with outward-facing lights and tremble alarms on the fences could be seen. Across the entrance ramp was the listed generator building – unusual to be separate for reasons stated earlier. The filler points for the diesel supply are clearly visible though the greatest threat the building currently faces is from the school bee hives on its roof! Nearby is one of the massive ventilation towers which lead deep underground into the plant area. Finally there is an external guardroom, built during the 1980s as an additional security precaution. This was the era of the cruise missiles and, just like Greenham Common, Daws Hill had its own peace camp of disarmament protestors.
Venturing underground, the first sight was of the massive blast doors which would have protected the bunker. Adjacent to these were two sorts of blast valves – one circular and one rectangular – designed to prevent blast waves from penetrating inwards. There are two entrances, the ‘clean’ and the ‘dirty’. The latter led through a decontamination suite in very good order, progressively through areas labelled as:
- Blast Lock
- Liquid Ingress
- Vapor Ingress
- Ingress Air Lock
- Dressing Room
I believe the Liquid and Vapor Ingress areas are connected with surface cleansing – possibly including biological and chemical contamination.
At the end of the decontamination area is an entry intercom and a viewing window from the adjacent guard room. Entering the bunker proper, a flight of stairs with a dog’s leg led to the bottom floor of the three storey bunker. Before entering the main structure, we were able to visit one of the fascinating aspects of the building. The main bunker is clearly constructed within an outer shell – effectively a bunker within a bunker. Thus an outer wall of around five feet of reinforced concrete surrounds an air void of around ten feet before the inner core with again around a five foot width. Sub Brit members may have seen this ‘bunker-within-a-bunker’ architecture within Cold War structures in Germany and Sweden but its use in a mid World War II structure is particularly rare if not unique.
We were able to make a complete circuit of this air void; possibly empty during WWII but used in the 1980s to house a large variety of plant and machinery. Multiple sewage tanks were followed by multiple non-potable water tanks. It seems that drinking water was held above ground near the generator building which seems to be a crazy reversal of logic; there being no artesian well apparent. Through airtight ‘knife edge’ doors the void continued with air plant and ventilation equipment (dehumidifiers and filters etc) next. As we progressed further into the hillside the height of the void increased from one to two to three storeys – a consequence of the stepped construction of the bunker referred to earlier.
In the far corner of the void were a full-height ladder and a hoist that we would see the top of later in the tour. Round the final bend was a corridor of major power handling equipment with vast cables stretching here and there. These were needed for the enormous 1980 mainframe computers used in the last stages of the bunker’s operation and high above enormous copper earthing strips made an impressive sight.
Having completed our circumnavigation of the bunker, the tour then entered the heart of the site. Starting on the bottom floor, the top secret nature of the operations within was apparent as door after door was labelled ‘Restricted Access TS (Top Secret) Clearance Required’ or ‘Restricted Area Level 6 Security Badge Required’ and so on. Many of the rooms had raised floors and major ventilation for computing equipment, all now removed. Like many US bases in the UK, all sockets were duplicated with UK 240V outlets doubled up with US 110V sockets. One area has a 208Vsupply which is 110V three phase. A control panel for the plant within the void (sewage, air conditioning, power etc) is seriously impressive with pride of place on the consol given over to an over-pressure indicator gauge.
The site had no dormitory or kitchen areas so once attacked conditions for those underground would have been quite primitive. There are however male and female toilets and these were of course inspected as is customary. One of the personnel rooms adjacent to a large computer room had hooks for four clocks on the wall –labelled as Washington, Local and FRG (Federal Republic of Germany). The fourth label had been removed – almost certainly (in the author’s view) having been for Moscow. What better souvenir for the last occupants?
Other traces remain such as the extensive pipework for Halon fire extinguishant, early-era movement detectors, loudspeakers and enormous earthing boxes. One of the rooms and some of the outlets are labelled for ‘WWMCCS’ or the (US Army) World Wide Military Command and Control System. Pronounced ‘Wimex’ this system provided military warning, communications, data collection and processing, and executive decision-making tools. It lasted until the mid 1990s and it is understood that Daws Hill was one of the few sites outside the USA to receive regular updates to the War Plan that was an integral part of it.
Floor by floor, the tours slowly ascended the three floors. Two staircases exist, one accompanied by hydraulically operated trap doors through which equipment for inside the bunker could be hoisted. The trap doors seem to be part of the original WWII fitout although they would have been ratchet and cable operated at this stage. The exterior walls of the whole bunker are all lined in steel – installed in the 1980s and part of a huge Faraday Cage. This protected equipment against the EMP (Electro Magnetic Pulse) of a nuclear explosion which, along with the blast wave and radioactive fallout, was the third of the main hazards of a nuclear explosion.
Those with a good sense of spatial awareness could envisage the ‘stepped’ nature of the three floors – as well as the evidence of the varying height of the void, the ceilings of rooms without accommodation levels above were also totally Faraday screened. On the middle floor, it was possible with a bit of deduction to place the original two-storey WWII Operations Room. There is an area of ceiling where a distinct lip can be discerned and later infill conjectured. The Operations Room would have been the nerve centre of the 8th Air Force Bomber Command, with tote boards showing current and forecast weather, squadron readiness, operations progress and so on and so forth.
On the top floor of the complex there are several rooms where condensation has caused the collapse of ceiling tiles and some of the raised floors are showing signs of weakness after the recent leak. Thankfully this deterioration has stopped once the root cause was addressed but it shows how even a small period can cause rapid deterioration in a building. The top floor also houses an extensive electrical plant room, complete with filters and voltage regulation equipment.
Back to the present day
There are a few reminders of the final roles that the bunker fulfilled. Some of the walls have damage believed to have been inflicted by US Marines who used the site for CQB (Close Quarter Battle) training in the 1990s. Even more mysterious are some strange runic symbols and strands of what appears to be cobwebs through part of the bunker. It turns out that these are from the Halloween parties authorised by the Base Commander after its operational closure.
Soon it was time for the tours too to return to the present day and the exit used the original emergency route which climbs up steep stairs from the top level of the bunker. A few original WWII wiring brackets can be seen, as can the top of the hoist over the void viewed at the start of the tour. The exit stairs are bracketed by an inclined railway which would have supported a cable hauled wagon to take materials into and out of the bunker. The exit point is well above the entry level and so a gentle surface descent brought us back to the start of our journey.”
The school is currently considering any potential commercial reuse of the bunker but has to consider the constraints of access to the site as the only means of getting to the bunker are through the grounds of the girls’ school. One possibility is limited use as a film set and the bunker has recently been used as a location for an episode of Midsomer Murders and the finale of a series called ‘Apocalypse Slough’ starring Rob Lowe.
Today, the bunker stands as a memorial to those of the 8th Air Force whether they served above or below ground. The countless B17 crews who lost their lives in World War II were counted out but not back from this historic structure.