Almost 1,000 people worked at Morfa Conwy, the beach and dune area, which is located to the far side of the Marina if you're standing outside the pub; where the estuary meets the sea. Among them was Olef Kerensky, son of a former prime minister of Russia. The men constructed three giant caissons, known as Hippos. Some components were fabricated in other places and transported to Morfa Conwy for assembly.
The structures were eventually towed to France and linked to form two harbour walls. They helped the Allies to take ashore large numbers of vehicles, personnel, communications equipment and other supplies – vital to sustaining the frontline forces as they pushed deeper into enemy territory. After the war, Albrecht Speer (the former Nazi minister of ammunition production) paid tribute to Hughes’ concept, describing it as an idea of simple genius.