Churchill Barrier No. 4, East Mainland, South Ronaldsay and Burray, Orkney Islands

Description

Churchill Barrier No 4, about 650m long, is part of a group of four 'Churchill Barriers' built between 1940 and 1944 to link islands at the eastern side of Scapa Flow. The barriers are solid causeways that prevent access from the east into the four channels leading to Scapa Flow, the main British naval base during the Second World War. The scheme was designed and supervised by Sir Arthur Whitaker, Civil Engineer-in-Chief of the Admiralty. The contractors were Balfour Beatty & Co Ltd. Italian prisoners of war who were interned at Lamb Holm formed part of the workforce that made the concrete blocks and built the structure.

In accordance with Section 1 (4A) of the Planning (Listed Buildings and Conservation Areas) (Scotland) Act 1997 the following are excluded from the listing: excluding concrete edge beam, crash barriers, modern road surfacing, car parking area and toilet block to northeast.

The defensive barriers were constructed to prevent ships and particularly submarines from entering Scapa Flow from the east, but they also provide road access southwards from Mainland to South Ronaldsay. Barrier 4 links Burray with South Ronaldsay. Although conceived and built at a time of national crisis, their lasting role has been as causeways and roads linking islands together.

Barrier 4, like the other barriers, has a base built using bolsters, wire cages or baskets that were filled with broken rock and then dropped into the water of the channel. Most of this deep structure is below water level. A road carriageway formed from dumped aggregate and horizontally laid concrete blocks overlies the causeway base.. Five and ten ton cast concrete blocks placed in varying positions on either side of the barrier at angles help to protect the causeway core and prevent the tide from overtopping the carriageway. In total, all four barriers required about 250,000 tons of stone rubble and 66,000 concrete blocks. The barriers now carry the A961 road south to South Ronaldsay. The barriers are numbered from north to south.

Statement of Interest

The Orkney Islands played a critical role in the Second World War as home to the main British naval base and Churchill Barrier No 4 was an important part the base defences. Construction of the barrier is itself an outstanding engineering achievement.

The Churchill Barriers were built during the Second World War at the instigation of Winston Churchill following a traumatic event of national significance – the sinking of the British battleship HMS Royal Oak by a German submarine. The barriers were required to seal the eastern approaches to Scapa Flow, the main anchorage, and they are unique in Scotland as extensive, solid anti-submarine defences forming causeways. The barriers are functional structures built of stone rubble and concrete blocks. They have a very high level of national and international historic interest and represent a notable civil engineering achievement. Their construction required experimentation and a customised solution to the problem of creating a stable structure to block fast flowing tidal currents, suggesting exceptional structural form. The barriers have a close historical association with Winston Churchill and with the defence of Scapa Flow in 1939-1945, and their surviving form directly illustrates their wartime function. There have been alterations to Barrier No 4 since construction, primarily the upgrading of the road causeway over the rubble core embankment in 1950 and the periodic replacement of blocks protecting the causeway sides. However, these maintenance works have not affected its interest in listing terms. The natural accumulation of sand to the east of Barrier 4 has had the effect of burying and preserving the early structure.

In accordance with Section 1 (4A) of the Planning (Listed Buildings and Conservation Areas) (Scotland) Act 1997 the following are excluded from the listing: concrete edge beam, crash barriers, and modern road surfacing.

Age and Rarity

The construction of the Churchill Barriers is described by Paxton and Shipway in their 2007 book 'Civil Engineering Heritage: Scotland - Highlands and Islands'. The barriers were built between May 1940 and September 1944 and were officially opened on 12 May 1945. Scapa Flow was the main British naval base during the Second World War. Its eastern approaches had been protected by blockships during the First World War, vessels that were moored or grounded in the channels in order to block them. But by 1939, the blockships had moved or deteriorated and in October a German submarine penetrated the channel between Mainland and Lamb Holm and sunk the Royal Navy battleship HMS Royal Oak with the loss of 833 lives. The Churchill Barriers were built in response to this event as part of the defences of the main British naval base; their construction cost £2 million.

Other forms of anti-submarine defences were used in Scottish waters, including anti-submarine booms and nets. However, in our current state of knowledge, the Churchill Barriers are the only UK example of an extensive, solid anti-submarine and ship defence built from stone and cast concrete. They are therefore a unique group of defensive structures.

The listing criteria state that buildings put up between 1840 and 1945 which are of special architectural or historic interest and of definite character may be listed. We consider the barriers have special historic interest and are of definite character.

Architectural or Historic Interest

Interior

N/A

Plan form

Barrier 4 links the small island of Burray with South Ronaldsay to the south. Together with Barrier 3 (see separate listing) and Barriers 1 and 2 (which are not listed) they form a continuous obstacle along the east side of Scapa Flow. The individual barriers are straight, with their orientation reflecting the location of the islands that they joined.

Technological excellence or innovation, material or design quality

Building long fixed barriers across bodies of tidal water presented unusual engineering requirements in the mid-20th century. In this period, solid causeways were not a normal response to civilian transport needs, with bridges or ferries usually preferred when open water had to be crossed. The barriers' designers had to take account of the fast flowing tidal water in narrow but relatively deep channels. Paxton and Shipway note that the barriers were designed to withstand a 4-5 knot tidal current, while Seath's 1946 paper provides technical details of the barriers' construction. Engineering research had to be undertaken before the barriers could be built, and this included experiments using models conducted at the Whitworth Engineering Laboratories at the University of Manchester, and trials of different types of bolster carried out at Deptford, London. A special feature of the construction operation was the use of aerial cableways to deposit the bolsters. Four electrically driven cableways were obtained from works on the Kut Barrages across the Tigris in Iraq, and one of these was deployed in the construction of Barrier 4.. Three generating stations were built to supply power. The Resident Superintending Civil Engineer was initially E K Adamson, then from 1942 it was G Gordon Nicol, whose notes and photographs are preserved in the Orkney Archives in Kirkwall and form a record of the construction work.

Construction of the Churchill Barriers was a major engineering feat that required initial research at the University of Manchester, and then customised engineering solutions during the build.

Setting

The setting of the Barrier No 4 remains largely unaltered from its setting at the time of construction, though natural processes have caused the formation of a wide deposit of sand on the east side of the barrier. Today, as in the 1940s, the barriers link islands with predominantly rural, agricultural landscapes, occupied by small settlements and dispersed farms. Also, their setting continues to reflect the military context of their construction: the remains of old blockships can still be seen protruding from the waters around Barrier 3. In addition, the contemporary Italian Chapel (1940-42), listed at category A, still stands on Lamb Holm, 5 km northeast of Barrier 4, where it was built by Italian prisoners of war who were working on the construction project.

Regional variations

N/A

Close Historical Associations

The Churchill Barriers were constructed in the aftermath of the sinking of the British battleship HMS Royal Oak on 14 October 1939. During the First World War, the anchorage at Scapa Flow had been protected by measures including the sinking of blockships in critical access channels. However, the defences had not been maintained during peacetime and the naval base was clearly exposed. In their book 'Scapa Flow', Malcolm Brown and Patricia Meehan note that on 31 October 1939 Winston Churchill went to Scapa Flow to meet Admiral Forbes and they agreed the comprehensive reinforcement of the defences, including more booms, blockships and batteries. Most of the work was to be completed by March 1940 but sealing the eastern approaches would take longer. Brown and Meehan state it was Churchill's view was that only solid concrete barriers could guarantee the security of the anchorage; on current knowledge the building of the barriers was due to his personal intervention. Brown and Meehan also suggest this was a psychological necessity as well as a strategic one, demonstrating visibly that the weakness exploited by the Germans on 14 October 1939 had been sealed.

Paxton and Shipway state that initially building of the massive causeways was undertaken by British and Irish workmen. However, the barriers became recognised as causeways for potential civilian use; this lead to a more relaxed interpretation of the Geneva Convention and from early 1942 up to 1200 Italian prisoners of war worked on the scheme. The Italians lived on Lamb Holm, where they created the ornately decorated Italian Chapel from two Nissen huts. The Italian Chapel is listed at Category A (LB12728).

Close associations with nationally important people or events can be a significant factor in listing. The barriers are well preserved in a form and condition that directly illustrates their associations with the fortification Scapa Flow in the years following 1939, a nationally and internationally significant military site.

External Links

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