Twatt Airfield (Former Hms Tern), Air-Raid Shelters Birsay and Harray, Scotland

Text courtesy of Historic Environment Scotland. © Crown Copyright, reprinted under the Open Government License.

Part of a B Group at Twatt Airfield including: Combined Control Tower and Operations Block; 5 Air-Raid Shelters; 2 Pillboxes (see separate listings). A significant grouping of five heavy-duty pre-cast concrete WWII air-raid shelters at the former Twatt Airfield and a good survival within their building type. Pragmatically located near to the officers and ratings quarters, this group of 50-man concrete shelters evidence the perceived threat and the importance of maintaining airfield operations in Orkney. The pre-cast unit construction is similar in form to the traditional Stanton-type shelters but the tapering arch shape in cross-section is unusual. The interest of the shelters is increased by the survival of other associated WWII structures at Twatt, the combined control tower and operations block (see separate listing) being of particular note. Of the four main military airfields in Orkney, Twatt has the most complete level of surviving WWII infrastructure with little remaining at Hatston, Skeabrae or Grimstter (Kirkwall). The surviving elements include 2 octagonal concrete pill boxes (see separate listing), the brick shells of the vehicle and parachute stores, ammunition stores, sick bay/decontamination unit and generator house and the projection room section of the former cinema. None of the aircraft hangers remain. The airfield at Twatt was begun in 1940 and commissioned as HMS Tern in 1941 as a satellite of Hatston airfield for the Royal Marine engineers. It remained in service until 1949. Air defences in Orkney were a significant contributor to national security with strikes from airfields in Orkney helping to counter U-boat, surface vessel and air threats over the North Sea and at Scapa Flow. The hub of the Royal Navy's sea base operations were located at Lyness at the entrance to Scapa Flow including the Wee Fea Naval Communications and Operational Centre (see separate listing). The airfield covered 440 acres of land in 1941 and was extended to a total of 564 acres in 1943. There are three abandoned 19th century farmsteads within the perimeter. Royal Navy Air Stations were separate from the Air Ministry and therefore developed their own distinct airfield architecture and layout, tending to have 4 intersecting runways rather than the 'A' plan layout favoured by the Air Ministry (RAF).