During the Second World War, the network of Chain Home radar stations was a crucial part of air defences for the UK, with the station at North Cairn aiding in the protection of Belfast and Glasgow. At the time, the station was top secret and many of those working there did not know the full extent of operations.
The Mobile Radar Unit (MRU) was the first form of radar in use at North Cairn. It would have consisted of a convoy of 10 vehicles, with tents, power generator, workshops, and a field kitchen. Two large trailers would carry the Transmitter and Receiver equipment, while the 75-foot masts would travel in several parts on four-wheeled trailers.
(image: mobile radar unit © IWM CH 15200)
Whilst the Mobile Radar Unit and Advance systems were operational the Final radar set up was built within two fields on North Cairn farm alongside the Advance buildings. Willie Jones, an employee on the farm, related that at the time, the fields were under crop and two weeks away from harvest, but the farmer was told there would be no harvest and the fields would become out of bounds.
The Advance radar system comprised a single channel MB1 mobile transmitter, which resembled an upright piano in shape. It was used along with 105-foot masts. Over the winter of 1940, storms caused damage to the masts, blowing one down and necessitating the use of the MRU again for a short time.
The station was split into the A-site (the top secret, technical operations area) and the B-site (accommodation and administrative buildings) located about a mile east.
Gerrards of Manchester were contracted to construct the Final system buildings for the station and many local men worked on the site. During construction, four or five buses carrying men and an additional one or two lorries would travel to the site every working day. Working on the A-site required a special pass due to the secret nature of the work there. The radar equipment itself was kept covered by black cloth while the workers were there. Sometimes, a buzzer would sound, and the workers had to vacate the site to allow the radar operators to do their work in secret.
After the buildings were constructed, equipment was brought to the site. On two occasions getting the equipment into the buildings required the walls to be breached with hammers and chisels and reconstructed afterwards.
Nineteen months after construction began, calibration was completed on the first broadcast channel, giving the radar station improved plotting performance. The second channel became operational in October 1943.
Throughout early 1943, equipment continued to be installed at North Cairn, including the Interrogator equipment which was part of the Identification of Friend or Foe (IFF) system. Calibration work was ongoing as each piece of new equipment or modification was completed.
On 5th of October, three years after construction of the Final system began, it became fully operational on two channels. The equipment from the Advance radar station was returned to HQ. The buildings from the Advance station were no longer needed but remained on site as backup buildings and as dummy targets for enemy attacks.
There was a general wind-down of the Chain Home radar stations from November 1943 onwards. This was due to the lessening of enemy activity, especially around the western coast of Britain. North Cairn saw a wind-down of its own operations from January 1944 onwards with a decrease in personnel and the relaxation of certain regulations.
The official orders to cease reporting radar plots came on 7 th March 1945, precipitated by the impending crossing of the Rhine by the British and American armies, signalling the inevitable defeat of Germany. North Cairn was put into ‘Care and Maintenance’ Stage 1, meaning that it could still return to operations with 14 days notice. In May 1945, North Cairn moved to Stage 2 ‘Care and Maintenance’, which would allow it to return to operations with 6 months notice.
After the end of the Second World War, the radar station at North Cairn was fully dismantled. The equipment, starting with the aerials on the towers, was taken down and returned to HQ. The towers themselves and the permanent buildings were left on site, and the land returned to it’s original owners, Stair Estates.
Since returning to its original owners, North Cairn has been subsumed into the life of a working farm. Some of the buildings were repurposed into byres, pigsties, and straw stores, while other features, such as the receiver tower bases have been removed and dumped nearby. The remaining transmitter towers were gradually taken down over the years, with the final one being removed in the 1980s.
Archival images in the timeline above: RAF Air Defence Radar Museum, unless stated otherwise.
This name carved onto the outside of the guardroom was barely legible during the survey. Using photgrammetric techniques a 3D surface of the wall onto which it was carved was created. This 3D surface was then visualised using a combination of multi-direction hillshading and local releif modelling to enhance the graffiti.
Acknowledgements
The survey of RAF North Cairn WW2 Chain Home Radar Station was by carried by AOC Archaeology as part of Dumfries and Galloway Council’s Rhins Revealed Community Archaeology Project, delivered during development work on the Rhins of Galloway Coast Path
AOC Archaeology are indebted to Ian Baldie who generously allowed us to use his work on the history of North Cairn in the production of this report. AOC Archaeology would also like to thank all of the volunteers who helped to undertake the survey.
