Tuesday 12 May is the 75th anniversary of the opening of the Churchill barriers that link Burray and South Ronaldsay to the Orkney mainland via Lamb Holm and Glimps Holm. The current situation has postponed a programme of events to mark the occasion, including the unveiling of a plaque, and instead engineer John Andrew and filmmaker Moya McDonald look back at the scale of the achievement.
The design and construction of the Churchill Barriers, undertaken by Balfour Beatty & Co Ltd between May 1940 and September 1944, was one of the most significant and complex civil engineering achievements of the 20th century, more so considering it took place during World War II.
These days it’s easy to take the barriers for granted, driving over them along the A961. But prior to the Second World War, travelling to and from South Ronaldsay meant catching the ferry from Stromness or Scapa Pier, bound for Scrabster.
From the mid-1930s there was the alternative of Gander Dowar’s Allied (Aberdeen) Airways which landed at South Ronaldsay’s Berriedale airfield by request. From Burray a ferry ran over to South Ronaldsay.
Preventing enemy attack on the Royal Navy’s main base at Scapa Flow by blocking its eastern approaches had been considered in World War I, but the prohibitive cost plus a possible 18 months construction programme (when many believed that the war would be over soon) saw it rejected in favour of the much cheaper option of strategically sunk ships – blockships.
The blockships proved successful throughout the First World War but once the war was over, they became a source of tension between the Admiralty and Orkney. The fishermen of St Margaret’s Hope, Burray and St Mary’s had hoped for their removal to allow, once again, easy access to the open sea but despite initial promises nothing happened until 1923 when a few were salvaged, and others moved.
There was no immediate change in the Scapa Flow eastern defences following the outbreak of the Second World War until U-Boat 47, captained by Kapitänleutnant Gunther Prien, successfully entered Scapa Flow through Kirk Sound, in the early hours of 14 October 1939 and sank HMS Royal Oak with the loss of 835 of her crew. First Lord of the Admiralty Winston Churchill, after visiting Orkney, ordered that the approaches should be blocked off permanently, no matter what the cost.
A formidable challenge
The task to construct the four barriers closing off Kirk Sound, Skerry Sound, Weddel Sound and Water Sound would be formidable. Five islands had to be linked by sealing the intervening four tidal channels – in total 9,150 ft across and up to 70 ft deep. Fast tides and 100 mile-an-hour Atlantic gales prevented stone being dumped from vessels; while end tipping from each island was impossible because the narrowing gap would have increased the tide to a fierce torrent.
If the method of construction was a problem, so too was the selection of material; in laboratory experiments, a three-foot cube of concrete dropped into 20 ft of water moving at the speed of the Scapa tides was swept 90 ft away, and the water at Scapa was three times this depth!
The contract to undertake this work was awarded to Balfour Beatty & Co. Ltd, a company founded in 1909 by George Balfour and Andrew Beatty, which had great experience of building hydro projects across remote areas of Scotland and was already working on several defence projects in Orkney including building new aerodromes and major construction work at HMS Proserpine, the Lyness Naval Base on Hoy.
Damming the flow
Balfour Beatty’s experience of building the Kut-el-Amara irrigation barrage across the Tigris in Iraq prior to the outbreak of the war was crucial to this operation and techniques used there were adapted for use on the Barriers. In Orkney wire nets were filled with local stone to make ‘bolsters’, similar to the desert sandbags used in Iraq, which when dropped from aerial cableways into the surging water clung firmly to the bottom and each other. These overhead cableways, which they had also used for some hydro schemes – known affectionately as Blondins after Charles Blondin the French tightrope walker and acrobat – were brought back from Iraq, refurbished and put to work in Orkney.
David Balfour, an engineer and director of the company, whose father George was one of its founders, was removed from his Army service by the Admiralty to get the project established. He had also been involved in the Kut project so had the extensive experience required.
Month after month, ton upon ton hurtled down from the cableways and disappeared without trace. Not surprisingly the project was referred to as ‘Rockworks’, an appropriate code-name for a project that was strictly classified.
Piers and POWs
Priorities for this major operation were the building of piers by hand to land the heavy equipment needed for the construction work and accommodation for the workforce at St Mary’s and on Lamb Holm and Burray. Accommodation was initially provided by the 15,551-ton SS Almanzora, which arrived early in May 1940 carrying 250 workers and much-needed heavy plant and equipment.
The Balfour Beatty workforce, which numbered 2000 at its peak, was supplemented by sub-contractors and, from early 1942, by Italian prisoners of war brought from North Africa to replace some of the Balfour Beatty personnel who were required to reinforce the war effort elsewhere. With the arrival of the Italian POWs the Barriers were classified as causeways to link the islands rather than barriers to block enemy attack.
Resourcefulness was a key requirement of the project with materials at a premium due to the ongoing war, and the blockship Ilsenstein, a 7,000-ton ex-German passenger ship, sunk in 1940 as part of the early stages of the project, provided many useful materials including steel wire ropes, thick plywood and even kitchen equipment.
The Italian POWs, housed in two camps on Lamb Holm and Burray, took resourcefulness to another level by converting Nissen huts into a chapel at each camp from donated materials. Only one survives, the exquisite Italian Chapel on Lamb Holm, made from two Nissen huts, and now one of the most visited sites in Orkney.
It took four years to close the channels but the impossible had after all been possible. It took half a million cubic yards of rockfill and aggregates acquired from eight quarries and 300,000 tons of concrete facing blocks manufactured at five concrete blockworks. Five electricity generating stations were also built and operated to provide the 1570kW of power required.
Nearly £350,000 (£16,000,000 in today’s money) was spent on plant and equipment for the construction of the works. This included twenty-four cranes from 3 tons to 10 tons capacity; nineteen excavators ranging from 3/8 cubic yard to 1¼ cubic yards; sixteen crushers, fifty-one lorries and twelve dumper trucks. The floating plant included two steam-tugs; two steam drifters; a diesel tanker; four launches; a 350-ton hulk and seven barges. There were also the five electrically powered cableways; two at Kirk Sound, east and west and one each at Skerry, Weddel and Water Sounds. The project also involved the laying of an extensive railway network with fifty-eight locomotives of 2-foot and 3- foot gauges and 260 wagons of all classes operating to shift the heavy materials required. There was once ten miles of railway track on Orkney!
Completion and opening
After 4½ years the work was completed to all intents and purposes by September 1944 and cost approximately £2,000,000 (£91,864,000 today). They were officially opened by the First Lord of the Admiralty, the Rt. Hon. A. V. Alexander, C.H., M.P., on 12 May 1945, connecting South Ronaldsay and Burray by road with the Mainland and changing life in Orkney forever.
After attending the events to mark the Barriers’ 50th anniversary in May 1995, Alistair Wivell, Balfour Beatty Managing Director and son of Sandy Wivell, the general foreman on the project, accompanied by John Andrew, also from Balfour Beatty, returned to Orkney to present an illustrated talk at the Orkney International Science Festival that September. John Andrew will give a presentation on the Barriers in this year’s Festival (3-9 September 2020) which will be delivered online and open to all.
A programme of events planned for this May by AOP (Another Orkney Production) to mark the 75th anniversary has had to be postponed but will take place at a later date. They include the unveiling of a ‘Red Wheels’ plaque, awarded by the National Transport Trust, only the fifth awarded in Scotland.
John Andrew is a Fellow of the Institution of Civil Engineers with over 40 years of experience and has a keen interest in historical civil engineering heritage. He has a deep and longstanding interest in the Churchill Barriers and undertaken significant research and presented papers on the construction.