The Mulberry Harbours were crucial to the success of D-Day and the liberation of Europe from the Nazi regime.

A prototype of the giant concrete floating harbours was built in Conwy, and designed by gifted Bangor-born Welsh engineer, Hugh Iorys Hughes.

In 1941 Mr Hughes, who was said to be quiet and unassuming, worked as a civil engineer living in London, when he submitted plans to the War Office.

The plans' potential value was not immediately recognised but Hughes' brother, a Commander in the Royal Navy, drew the plan to the attention of more senior officers. It was the beginning of a long association Hughes had with the Mulberry project.

About 700 workers were drafted in to work on the clandestine project in 1942, consisting of carpenters, steel erectors, welders and labourers as well as office staff were employed at the site and accommodation had to be found for them all.

The council were so worried about finding the necessary accommodation that they considered "asking for an order to send out of the borough the people who have come in after a certain date".

Working conditions were poor, with little or no cover from the elements and men riveting and welding at great heights.

The blackout just had to be ignored. Residents got used to the hammering and striking at this new ‘shipyard’ but with the government mantra of "Careless Talk Costs Lives" asked no questions and when enough sections were prepared at Conwy Morfa, they were floated up the coast to Garlieston in Wigtown Bay, near Dumfries in Scotland, for testing.

A plaque on Conwy Morfa to commemorate the construction in this area of concrete sections of Mulberry Harbours used in the D-Day landings in 1944.

The former Mayor of Conwy Betty Pattinson, who passed away this week at the age of 91, talked to North Wales Live in 2017, about her memories of the construction work.

The keen local historian who was a teenager at the time, said: "Conwy was really busy at the time. There were lots of workers, some who stayed in my house and military around.

"We knew something was being built, but nobody knew what it was and you weren’t allowed to get close to it."

She added: "When we found years later what it was, it was very impressive and the idea for a plaque dedicated to its construction came from one of my exhibitions."

Troops using a Mulberry harbour during the D-Day landings in 1944.

A memorial stone and plaque stands today close to Conwy Marina commemorating the work of the people who worked on the project.

By the summer of 1943, up to 45,000 personnel became involved in the project with the bulk of the work carried out on the River Thames and River Clyde.

But it was only in June 1944, when the Allied forces launched the D-Day Landings in Normandy, France, the purpose of the creations became clear.

Tom Jones, a D-Day veteran from Prestatyn was awarded the Legion d'honneur, the highest French order of merit for military and civil merits last year. Photo by Ian Cooper

Last year North Wales Live spoke to Tom Jones, a 93-year-old from Prestatyn, who who a veteran of the Normandy Landings.

As a 19-year-old he was involved with towing Mulberry Harbours for the Allied invasion. Last year Mr Jones was given the Légion d’Honneur by the French government to honour him for risking his life to secure France’s liberation during World War II.

A former Royal Navy man, Mr Jones said he remembers D-Day and as if "it happened yesterday".

The largest seaborne invasion in history started on Tuesday, June 6, 1944 and laid the foundations of the Allied victory on the Western Front.The Mulberry Harbours had to carry heavy tanks and artillery, withstand summer gales and be moveable from one beach to another.

Mr Jones said: "It was a dangerous job, and you really didn’t know whether you were going to make it back alive.

"The sound of the German guns nine miles away hurt our ears they were so loud.

Parts of the Mulberry Harbours that were used on D-Day can still be seen on the beaches of Normandy.

"Shells were going off all around us, and it was bang, bang, bang all the time!

"I remember the sky was black with fighter planes, but as well as terror it was pretty exciting stuff for a 19-year-old, a day out to see the guns."

Local historian Adrian Hughes has written a new book- 'The Second World War in the Borough of Conwy' published by Conwy Town Council. Amongst the wartime stories is the 'Mulberry' harbour construction. All proceeds from the sale of the book, priced at £5 will be divided between the Poppy Appeal and Citizens Advice Conwy. It is available from the Guildhall in Conwy.

There is a ceremony to mark D-Day at the Mulberry harbour stone starting at 2pm on Sunday, and afterwards at the Guildhall at 3pm.