The P-DASH Test Array







Sources and Recommended additional reading by Dr Bob Clarke

"The Illustrated Guide To Armageddon ISBN 978-14456-0915-7"

“Four Minute Warning, Britain's Cold War ISBN 0-7524-3394-6”

Running on an alignment of magnetic north at 350 degrees, the remains of a version of the experimental “P Dash” array can be found on the SE corner of the airfield.   Nothing remains today except a scar in the concrete running for approximately 1km from the centre of the original runway #2, through woodland, eventually breaking out onto the perimeter track remains just adjacent to the entrance to the incendiary store part of the bomb dump.  

P Dash was intended to be an ‘over the horizon radar’ system that was designed to monitor Russian Nuclear Attack Submarine movements in the Baltic Sea during the Cold War and was originally scheduled to be up and running by 1993 - trials were being undertaken earlier than officially announced at Blakehill, which was (believed only partially) to be the reasons for the strict secrecy surrounding the site.    Other experimental works were being carried out with other aerials and arrays at BHF which will be examined when information is released.    It is believed that the experimental version of P-Dash was used to monitor weather conditions in the North Atlantic during this early trial (at least officially anyway!)

The receiving building for the array was an acoustically modified hut, now known as the Whitworth Building.   This building was full of sound deadening cones which remained up until Wiltshire Wildlife took over the site.    Sadly all of the sound deadening equipment was disposed of.

The full scale P Dash array was never built due to the fall of the Soviet Union.    General Secretary Mikhail Gorbachec resigned on the 25th Dec 1991, and by 31st December the formal dissolution of the USSR had taken place.     The cold war was over.


If it had been built, P Dash would have been one of the world's largest radar arrays, with RAF Blakehill being the ‘Reciever’ site, whilst the ‘Transmitter’ site was 150 miles away to the west at RAF St Davids in Pembrokeshire.

The array would have looked like two rows of street lamps - similar arrays have been built around the world since - a Google search of OVER THE HORIZON RADAR will show you .    The array worked by radio signals being steered and transmitted to bounce off the ionosphere to reflect onto the target area below.    This then reflected signals from the target area, back up to the ionosphere where it reflected back to the receiver station to be interpreted.

The transmitter station at St David’s would have required an 85m long array with the required restricted areas encompassing 45 acres.   The St Davids array would be made up of thirty five aerial masts, 16 of which would be 45m high. (source B Clarke)


The control centre at BHF would have been run by British and USA teams and around 60 military staff – at St David’s a temporary building and 15 equipment containers would be sited staffed by 19 civilians. (source B Clarke)


The project cost £11 million with the UK preparing the sites, designing all structures, and construction work.    Operating costs were set to be 3 million per year for 2 years – arrays would be built in USA and shipped over to the UK by the US Government – construction was to start in 1991 at both UK sites, but as described, international events over the time took over as the perceived Soviet threat ended. (source B Clarke)


Projects such as OTHR were cancelled and Blakehill’s experiment fell silent.   RAF St David’s saw its own progression to become a wildlife haven and is now owned by the National Trust, Blakehill Farm is owned of course (mostly) by the Wiltshire Wildlife Trust.

What remains today?

Like much of the former air station, so much has now been removed or has returned to nature, it is difficult for the causal visitor to appreciate the remains from ground level.


What remains is around a 1000 metre long trench that has been back-filled with gravel and concrete and is mostly obscured by trees.  Boxes made from fibre-glass containing the switching gear to steer the beam from the antenna to the target were situated along this line with a robust power supply running to the array.  The bases of these boxes remain.   One source has described a 100kW short wave transmitter glowing in the gloom within the receiver building and then a screened room with a computer processing the data.   Stumps of posts remain mostly identifiable on the farm yard section (PRIVATE LAND) and are located 15m away from the central trench, spaced around 6m apart.   There is another feature known as the 'Plunger' which requires further investigation.

From the remaining southern extremity of the scar (at least as far as one can venture due to vegetation) the scar runs on an alignment of 350 degrees across the farm yard, the first section covers 48m until reaching a pair of steel upright rods which are within an area of bramble.   These were possibly metal conduits.  

Following on from this feature, the scarring extends for another 59m, crossing the original runway centreline before reaching the next obstacle, one of the equipment barns belonging to the WWT.    Measured from the rear elevation of the barn, the scar then travels for another 53m before being lost again in undergrowth.


At the next available point of reference (ON PRIVATE LAND LOCKED AND GATED) the scar clears from the woodland to cross a disused spectacle dispersal, finally appearing out onto the remaining perimeter track.    The remains of one of the “equipment box” hard standings is evident.

The extreme northern end of the scar ends with the filled in gravel trench and the remains of a mast - below

One thing is for certain - if the cold war had continued, Blakehill would be a VERY different place today.


Deadly force would have been used on any casual visitor.

Information regarding RAF St Davids



St David's Airfield, Solva consisted of thirty diamond-shaped hard-standings which were placed in five clusters around the perimeter, the most extensive clusters being to the north. The bomb store and fuel store were also placed on the northern perimeter, with the bomb dump further to the north. The south side of the

airfield was the area determined for a watch office to pattern 12779/41, living quarters, and various maintenance buildings formed from Nissen or Maycrete huts. Provision for four T type hangars was also made on the southern perimeter, but only three were erected. Three Blister hangars were also built. The airfield had three runways 1801m (5910ft) long, 975m (3200ft) long, and 1088m (3570ft) long, established in a triangular pattern. The majority of buildings have now been demolished, but the runways and taxi-areas remain.

St Davids was initially intended to be a base for the US Navy with Consolidated Vultee PB4Y Liberators, but in September 1943 it opened for RAF Coastal Command units instead. The first aircraft were Boeing B17 Flying Fortresses from 206 and 220 squadrons. 517 Meteorological Squadron brought two Handley Page Halifax bombers in November 1943, followed in December by the Halifaxes and Hawker Henleys from 58 and 502 squadrons. 517 Squadron moved to Brawdy when it opened in February 1944. However, 58 Squadron was in residence at St David's until August 1944, and 502 Squadron until September 1944. 202 Squadron returned between June-September 1945 along with 53 Squadron (both equipped with PB4Y Liberator aircraft). The station's headquarters was moved to Brawdy along with the sick bay and workshops facilities in November 1945. St Davids was then placed into care and maintenance before both airfields were passed to the Royal Navy on 1 January 1946. Between 1955 and 1958, whilst Brawdy was being modernised to accept jet aircraft, St Davids was used by the Fleet Requirement Unit (FRU) operated by Airworld Ltd.


Below - St Davids as it is in 2017  

Gallery images of the P Dash remains - click to enlarge: