Today the lake is a tranquil spot for fishermen and a beautiful backdrop for reflective walks along the shore.

However, for those who know where to look, the signs are still there of the hectic wartime period when tanks arrived to shake a Norfolk village out of its rural somnambulance.

From the spring of 1943, British, American and Canadian soldiers descended on Fritton Lake, near Great Yarmouth, for top-secret preparations for the D-Day landings.

The pristine stretch of water, part of the Somerleyton estate, was requisitioned by the 79th Armoured Division to trial 'swimming' tanks which would provide vital support for infantry during the Normandy landings.

The activities, which were hidden from villagers by high fences and massive security, will be recalled during the weekend of June 4 and 5 when Fritton Lake, now a popular visitor attraction, puts on a special D-Day celebration.

More than 20 military vehicles are expected to attend, including a locally-owned Sherman tank and a Valentine duplex drive amphibious tank.

Lake manager Stuart Burgess has researched the colourful episode, interviewing locals who remember it and veterans who took part, and will give slide-illustrated talks; Suffolk historian Ian McLachlan will also give a presentation.

There will also be boat trips to view the places where the specially-adapted tanks took to the water and came ashore and displays by a second world war re-enactment group.

The problem of making tanks weighing more than 30 tonnes float had been overcome by Hungarian-born designer Nicholas Straussller who invented a collapsible, rubberised canvas screen that was secured on special plates welded to the tank just above the running gear.

When inflated, these provided sufficient buoyancy to enable the tank to float with only 3ft of the screen showing above the water line and the bulk of the menacing vehicle hidden.

Mr Burgess said: 'There was very restricted access to the site with road blocks in the village and high fences around the site. There was even camouflage netting in the trees where the tanks were parked and some of the metal ties are still there up in the branches.'

A concrete track built for the Sherman and Valentine tanks remains apparent and the site is constantly giving up its secrets with the discovery of everything from pieces of armour plating to guide horns fitted to the tanks' caterpillar tracks.

Mr Burgess believes that the biggest secret could yet be the discovery of a tank sunk and forgotten on the bed of the lake, along with the known military air sea rescue plane which crashed there towards the end of the war.

He said one local he had spoken to had recalled how when the tanks arrived on low-loaders they were instructed to draw their curtains.

Another interviewee, John Chapman, now living in Yorkshire, had told him how his family had farmed fields next to the lake during the war.

As children they had helped at harvest time but had to obtain permits from the military before they were allowed on to the fields; they were forbidden to venture into the wood or approach the lake but were aware of the secret activities.

The soldiers were at first billeted at guesthouses in Gorleston and Yarmouth but later lived in huts on the site. Mr Burgess said: 'They lived on military rations but there are stories of them lobbing hand grenades into the water and catching the fish that came to the surface.'

stephen.pullinger@archant.co.uk

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