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Churchill Barriers, East Mainland-South Ronaldsay, Orkney HY 483012- ND 476948 Scapa Flow was ideally suited to serve as the wartime fleet anchorage for the Royal Navy in both World Wars. However, the four main channels on the eastern side of the Flow were known to be weak-spots in its defence, and in the first war blockships were sunk as a protection against enemy submarines and torpedo-carrying craft. The inadequacies of the blockships were exposed in October 1939 when a German U-boat found a way round them in Kirk or Holm Sound, the deepest and fastest-flowing of these channels, torpedoed the battleship HMS Royal Oak, with the loss of 833 lives, and escaped by the same route. This dramatic episode at the very start of World War II prompted the construction of permanent barriers across the four channels, authorised by Churchill himself after a visit in person in March 1940, hence their name. Not finally breaking the surfaces of the channels until 1943, the barriers became recognised more as causeways for potential civilian use, and a relaxed interpretation of the Geneva Convention allowed the labour force to be augmented substantially by Italian prisoners-of-war from early 1942 onwards. Costing some £2 million, the works were completed in September 1944 and were officially opened on 12 May, 1945. The contractors for this remarkable feat of engineering and organisation were Messrs Balfour, Beatty & Co Ltd. The scheme was designed and supervised by Sir Arthur Whitaker, Civil Engineer-in-Chief of the Admiralty, and was carried out under the direction of H B Hurst who was succeeded by C K Johnstone-Burt, Herbert Chatley and J A Seath. Until 1942 the Resident Superintending Civil Engineer was E K Adamson, and from 1942 until completion it was G Gordon Nicol, whose notes and photographs preserved in the Orkney Archives in Kirkwall constitute a valuable record of the work of construction. A special feature was the use of five aerial cableways or ‘Blondins’ by John M Henderson & Co Ltd, Aberdeen. The structure of the four barriers consists of a core of rubble bolsters cloaked by 10-ton concrete blocks, which are in turn overlaid by 5-ton blocks, the outer skin being laid in 'pell-mell’ fashion to break the force of the waves. They measure some 2.3km in overall length, linking East Mainland to South Ronaldsay via the three islands (north-south) of Lamb Holm, Glims Holm and Burray. The widest and deepest channel was the northernmost, Kirk or Holm Sound between Mainland and Lamb Holm, where the foundations of what became No 1 Barrier were laid in fast-flowing tidal water up to 18m in depth. In total, the barriers absorbed about 250,000 tons of quarried rubble overlaid by some 66,000 concrete blocks from the casting yards at St Mary’s and on Burray. The sites of the rubble quarries, the concrete blockyards and the associated railways are still traceable on the ground, and a chapel on Lamb Holm, cleverly wrought out of two Nissen huts, remains a picturesque memorial to the Italian contribution.
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