Hugh Iorys Hughes
born  16th April 1902, 4 Garfield Terrace, Bangor, Gwynedd, Wales, UK
died  16th August 1977, West Mersea, Colchester, Essex, UK
buried  ashes scattered on the Menai Strait
era  Modern
A biographical summary
Welsh civil engineer Hugh Iorys Hughes — expert sailor with a lifelong interest in boat design — was one of the several leading UK engineers who worked on the top-secret Mulberry Harbour project in World War II in preparation for the allied D-Day landings on the French coast (Operation Overlord). A shy man who never talked about his achievements, Hughes deserves wider recognition for his war work and for his significant concrete structures on land that we still use today.
Hughes grew up on the north Wales coast near Conwy, where he spent a lot of time sailing — a pursuit he would continue all his life. He was educated locally, followed by engineering studies at the University of Sheffield. On graduation, he joined the consultancy of innovative structural concrete designer Owen Williams (1890-1969), where he spent the first 15 years of his career, acting as senior resident engineer on a series of notable concrete buildings and bridges.
When the Second World War broke out in 1939, Hughes tried to join the Royal Navy but was refused, as engineering was a reserved occupation. Following the Dunkirk evacuation of 1940, the importance of controlling a port to supply the army was clear, if an invasion of occupied Europe was to succeed. In December 1940, Guy Anson Maunsell (1884-1961) proposed towing precast hollow concrete units across the Channel and linking them together to form harbours or jetties. Early in 1941, Hughes envisaged concrete caissons and roadway units to perform a similar function.
Both ideas were put to the War Office but went no further, until Hughes' brother Sior (1910-82), a Royal Naval Volunteer Reserve commander, brought Hughes' plan to the attention of senior officers. In June 1942, Hughes was asked for proposals. His design was among three selected for evaluation. All had to carry heavy tanks and artillery, withstand summer gales and be moveable from one beach to another.
In October 1942, construction of three prototype concrete caissons with steel towers (code named 'Hippo') and two steel bridging road units (code named 'Croc') commenced at the Conwy Morfa sand spit. Astonishingly, even with around 1,000 men on site, supervised by Hughes and engineer Oleg Aleksandrovich Kerensky (1905-84), the work remained secret. By May 1943, the gigantic prototypes were ready to move and they were towed to Scotland for full-scale trials.
The plan for the Mulberry Harbours was now coming together, using elements developed separately around the country. Hughes' Hippo design was modified to form the Phoenix caissons to be used as breakwaters, developed by Oscar Faber (1886-1956). Hughes' commitment was such that Prime Minister Winston Churchill (1874-1965) invited him to act as a consultant. He was offered the (temporary) rank of Colonel but refused. The extraordinary task of constructing enough elements to build two harbours for the D-Day Landings now commenced.
Hughes lived and worked at Selsey Bill, West Sussex, and at Dungeness, Kent — the principal coastal sites where completed caissons were parked before dispatch. Disguised as a French fisherman, he made several visits to Normandy to take soundings and record tidal movements. He also developed methods for towing, sinking and anchoring the caissons, and he helped with installation of the breakwaters in June 1944. His role in translating the ideas behind Mulberry into practical form was disclosed to Parliament on 21st December 1944.
In peacetime, he returned to his London office and large-scale reinforced concrete construction. He also returned to ocean racing. In 1946, he skippered the yawl Lafita across the Atlantic to compete in the Bermuda Race (Newport, Rhode Island to Bermuda), coming fifth. While in Bermuda, he won a race against local sailors, before completing a record passage home from Bermuda to Cowes, Isle of Wight. On his return, he married Jane Vernon.
Hughes died in 1977, aged 75. One obituary describes him as "a delightful companion, having a likeable sense of humour, coupled with a modesty so unassuming that only his close friends appreciated his outstanding qualities". His ashes were scattered on the Menai Strait.
1902 Born 16th April in Bangor, Wales, fourth child of Owen Rowland Hughes (1864-1952, draper) and Mary Catherine Hughes (b. 1869, same surname, no relation), with siblings — Violet Helen Mary (b.1895), Leslie William Alfred (1898-1960), Guinever [Guenever] (b.1899), Richard Alwyn (1906-73) and (Alain) Sior (1910-82)
1913-19 Attends Friars School in Bangor, described as "highly-strung", with "sandy curls and a slight stammer, which he disguised by talking slowly"
1919-c.23 Attends Sheffield University, first class honours degree in engineering despite almost withdrawing from finals through nerves
c.1923-38 Senior resident engineer for Owen Williams (1890-1969) on bridges and other large concrete works in Scotland and in London
1924 Becomes (18th November) student attached to Institution of Civil Engineers (ICE)
1930 Elected (10th December) associate member of ICE
1938-40 Working as consulting engineer from offices at 66 Victoria Street SW1, London, living at 30 Pembridge Gardens, Kensington
1941-44 Working on the Mulberry Harbours, draws up proposals (dated 17th June to 6th August 1942), constructs three Hippos and two Crocs on Morfa Conwy, first Hippo launched 4th May 1943, followed by rigorous testing at Rigg Bay, Scotland, consultant on construction, deployment and installation of Phoenix caissons for Mulberry Harbour breakwaters
c.1945 War Office payment for Mulberry Harbour work delayed and fee reduced fee, he agrees (not wanting to appear as a war profiteer), costs barely covered, ends the war in a worse financial position than when he started
1946 Marries Jane Vernon on return from Newport to Bermuda sailing race, in which his yawl Lafita was placed fifth, also sails 2,850 nautical miles (5,278km) between Madeira and New York
1954 Founder member of the Ocean Cruising Club — members must have completed a non-stop ocean passage between two ports at least 1,000 nautical miles (1,852km) apart, also later a member of Royal Thames Yacht Club, West Mersea Yacht Club, Conwy Yacht Club and Royal Ocean Racing Club
1958-62 Designs and supervises construction of underpasses and subways at London's Hyde Park Corner, part of the Park Lane Improvement Scheme
1958-67 Designs and supervises construction of Blackwall Road Tunnel southbound (road tunnel), London
1960 Suffers a heart attack but makes a full recovery
1967 Compiles a series of notes (27th February) on his role in Mulberry Harbour project
1968 Retires to Besom House, 94 Coast Road, West Mersea, Essex
1977 Dies (16th August), survived by his wife, ashes scattered on Menai Strait
1978 Commemorative stone unveiled (6th June) at Morfa Conwy to mark the site of Hippo and Croc construction, exhibition held at Conwy's Guildhall
Selected works
Wembley Stadium (original) (resident engineer), Wembley, London, UK .... c.1923-24
Findhorn Bridge (resident engineer), Tomatin, Highland, Scotland, UK .... 1924-26
Montrose Bridge (resident engineer), Montrose, Angus, Scotland, UK .... 1927-30
Empire Pool (now Wembley Arena) (resident engineer), Wembley, London, UK .... 1933-34
Mulberry Harbour prototypes (design and construction), Morfa Conwy, Wales, UK .... 1941-43
Mulberry Harbour prototypes (testing), Rigg Bay, Garlieston, Scotland, UK .... 1943
Mulberry Harbours (implementation), southeast England, UK, and Normandy, France .... 1943-44
Cutty Sark dry dock, Greenwich, London, UK .... 1954
Park Lane Improvement Scheme (Hyde Park Corner underpasses and subways), London, UK .... 1958-62
Blackwall Road Tunnel southbound (approaches), Poplar to Greenwich, London, UK .... 1958-67
All items by Hugh Iorys Hughes
Everything built ... 1902 - 1977
K.J. Thomas, H. Iorys Hughes, Panel for Historical Engineering Works Newsletter, ICE Wales Cymru, 12th September 2009
Biographical information: Hugh Iorys Hughes, Iorys Hughes collection, Institution of Civil Engineers, London, c.1978
Obituary: Hugh Iorys Hughes, bound volumes of obituaries collection, Institution of Civil Engineers, London, 26th January 1978
Further reading
Prof. Sir Alan Harris, The Mulberry Harbours, Transactions of the Newcomen Society, London, 9th May 1990
Max Hastings, That Fatal Shore, Bonhams Magazine, Issue 39, p.3, Summer 2014
Mark Hughes, Conwy Mulberry Harbour, Gwasg Carreg Gwalch, Llanrwst, Wales, 2001
Cliff Jones, If at first you donít succeed, The Old Dominicansí Association Newsletter, Friars School, Summer 2010
K.J. Thomas, Draft letter to New Civil Engineer about H. Iorys Hughes, (unpublished) May 2009
Nigel Watson and Frank Turner, Maunsell: the Firm and its Founder, AECOM Technology Corporation, Hong Kong, 2005
Progress of the Park Lane Improvement Scheme, The Engineer, London, pp.698-699, 28th October 1960
The changing traffic pattern in Central London &endash; the Hyde Park Corner &endash; Marble Arch improvement scheme and the Park Lane underground garage, Concrete Quarterly, London, Number 56, pp.6-11, January-March 1963
With grateful thanks to Tony Millatt, Mersea Museum, and Medwyn Parry, RCAHMW, for additional information.
portrait  Hughes in a diving suit, probably taken in the 1920s after inspecting bridge foundations in Scotland, courtesy Gwasg Carreg Gwalch

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Hugh Iorys Hughes
This biography was funded by
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Institution of Civil Engineers
© 2022 Engineering Timelines
Friars School, Bangor
Hughes attended the Friars School in Bangor, which occupied this building 1900-99, now part of the Coleg Menai.
Photo: public domain
Wembley Stadium 1924, site of
The distinctive concrete towers of the original Wembley Stadium (1924, dem. 2012), designed by architect Simpson & Ayrton with engineer Owen Williams (1890-1969). Hughes was Williams' site engineer for the project.
Photo: © Merv Payne and licensed for reuse under this Creative Commons Licence
Findhorn Bridge
Hughes worked for Williams for 15 years, acting as resident engineer for a number of concrete structures, including the Findhorn Bridge (1926, pictured) and the Montrose Bridge (1930, dem. 2004), both in the Scottish Highlands.
Photo: © Ian S and licensed for reuse under this Creative Commons Licence
Cutty Sark in dry dock, Greenwich
In 1954, Hughes completed the original stepped concrete dry dock installed at Greenwhich for the famous tea clipper Cutty Sark (launched 1869). He also retrieved timbers from HMS Conway (1859), which sank in the Menai Strait in 1953, for use in the Cutty Sark's conservation. The dry dock was refurbished and roofed in 2012.
Photo: © Rienk Mebius and licensed for reuse under this Creative Commons Licence
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Before the construction of the Mulberry Harbours proper, the designs proposed by various engineers were evaluated using prototypes. The picture shows a Hughes prototype 'Hippo' concrete caisson under tow off Conwy, Wales, in 1943, at the start of its journey to Scotland for testing. Three Hippos were built, each weighing 6,100 tonnes.
Photo: from Conwy Mulberry Harbour by Mark Hughes, courtesy Gwasg Carreg Gwalch
Hippos and Crocs assembled in open sea at Rigg Bay, Garlieston, on the west coast of Scotland. The location was chosen for the tests as the topography was similar to the Normandy beaches. Models were also tested, and these indicated a need for breakwaters. The Hippo idea was developed into the Phoenix caissons used in Normandy for this purpose.
Photo: from Conwy Mulberry Harbour by Mark Hughes, courtesy Gwasg Carreg Gwalch
Looking along Hughes' Croc roadway (or pier), designed to bridge the caissons once the Hippos were sunk into position. A flexible steel roadway designed by Major Allan Harry Beckett (1914-2005), was eventually adopted instead for the pier elements.
Photo: from Conwy Mulberry Harbour by Mark Hughes, courtesy Gwasg Carreg Gwalch
View of the vast array of floating quays and roadways of Mulberry Harbour B at Arromanches, Normandy, taken on 27th October 1944. Phoenix caissons are visible on the right, forming a breakwater. Mulberry B was used by British and Canadian troops, and operational from June to November 1944. Mulberry A, used by the Americans, was damaged beyond repair by a storm on 21st June 1944.
Photo: courtesy Imperial War Museum collections
Phoenix caissions in 1990
The remains of Phoenix caissons off the beach at Arromanches in September 1990. The elements of the two gigantic Mulberry Harbours were constructed in less than a year by some 550 contractors around the UK. More than 2.5 million men were landed, along with half a million vehicles and countless tonnes of supplies.
Photo: © Chriusha / CC-BY-SA-3.0 / Wikimedia Commons
Memorial, Conwy, Wales
Memorial plaque on the foreshore northwest of Conwy Marina marking the site where the prototype Hippo and Croc units were constructed. Unveiled 6th June 1978.
Photo: courtesy William Day, Hyder Consulting UK Ltd
Hyde Park Corner underpass construction
The Hyde Park Corner underpass under construction, May 1962. Hughes designed the underpass and subways, completed later that year as part of the Park Lane Improvement Scheme.
Photo: © Ben Brooksbank and licensed for reuse under this Creative Commons Licence
Southbound Blackwall Tunnel, River Thames, London
Hughes consulted on the design of the approaches to the southbound Blackwall Road Tunnel (1967), running under the River Thames between Poplar and Greenwich in London. The main tunnel was engineered by Mott Hay & Anderson.
Photo: © David Dixon and licensed for reuse under this Creative Commons Licence