(CNN) — In their lifetime, they've shot down 22 Nazi warplanes, more than 30 V1 flying bombs, sunk one submarine and introduced rock and roll to the teenagers of Britain.
Now almost 70 years later, the Red Sands Forts in the Thames Estuary could live again as a complex of luxury hotels.
Originally built in 1943 as a series of connected platforms for anti-aircraft guns -- dubbed Maunsell Forts after their wartime designer Guy Maunsell -- the bizarre structures were designed as a deadly welcoming party for German warplanes on raids across the English Channel during World War II.
Built seven miles off the Kent coast near Whitstable, they later hosted pirate radio stations in the 1960s, transmitting pop hits deemed too risque for Britain's then-monopoly broadcaster the BBC.
Today, the rusting war relics rise from the shallow waters of the Thames Estuary like science fiction props from a version of the H.G. Wells classic "War of the Worlds."
Business consultant David Marriot Cooper tells CNN the idea for the hotel came out of a chance meeting in a pub in a nearby seaside town.
"I was in a bar in Whitstable just before last Christmas and got talking to someone who had an interest in preserving the forts," says Cooper, who has been behind other large restoration projects including a proposal to restore a pier at Herne Bay, farther down the coast.
"I was asked what I did for a living and was then told that I seemed to be the right person to come up with an idea to preserve the forts."
All at sea: The proposals include a helipad and hovercraft jetty.
Courtesy Aros Architects
He says turning Britain's coastal defenses into hotels already has a strong precedent with the 19th-century stone fort on the Solent River near Portsmouth. In 2012, it was converted into a nine-suite luxury spa retreat.
"With this in mind I thought that a hotel in the middle of the Thames Estuary was a brilliant idea," Cooper says. "I've been out there three times now and my idea for a hotel is, I believe, the only way to preserve the forts having seen them from very close range.
"It is a very magical experience out there."
He approached London-based Aros Architects who came back with drawings for a 44-room hotel in the gun towers, sundecks and terraces, a museum, a helipad and a landing jetty for a hovercraft.
According to Jenny Fitzgerald, associate director at Aros Architects, the project had to tread a fine line between converting the structure into a modern hotel and retaining its historical integrity. She says the complex would resurrect interconnecting catwalks between the gun towers that were removed for safety reasons in the 1970s.
"The affectionately named 'rubber ring' concept proposes a new central hub around the old 'control tower' with hotel foyer, restaurant, banqueting space and spa," Fitzgerald says.
Grueling tour of duty
"This hub would be linked by glass walkways, in place of the historical bridges, to the 'gun towers' that house the hotel accommodation, including executive suites in glazed extensions to the towers.
"A museum, dedicated to the ingenuity of Guy Maunsell, civil engineer and designer of the forts, is proposed within the 'searchlight tower' with its own separate arrival jetty."
The proposal is now in the hands of branding experts as the idea edges closer towards gaining consent from authorities. The forts themselves were decommissioned by the Ministry of Defence in 1956 and currently have no owners.
Nevertheless, Crown Estates -- which manages all land under the control of the British sovereign -- owns the seabed and any application would ultimately need its consent.
It's estimated that at least £40 million ($61 million) would be needed to get the wartime forts into serviceable condition. The gun towers were originally commissioned in 1942 and deployed in 1943 at a cost of £724,000 (nearly $1 million). The concept involved constructing the 760-ton towers on land and then towing them out to sea on barges where they were sunk on concrete bases in the shallow waters of the Thames Estuary.
The two-story structures -- each designed to house 165-265 men on grueling four-week tours of duty -- were topped with 94mm heavy anti-aircraft guns and 40mm Bofors light anti-aircraft guns.
The towers took eight weeks to build but could be put in position in less than eight hours.
The towers resemble alien craft from a version of "War of the Worlds."
Courtesy David Cooper
Such was the danger and urgency of the task during wartime that the Bofors light guns were installed first to shoot at enemy aircraft that could have swooped on the towers before they were put in place.
While their searchlights and radar could identify and detect enemy bombers that often used the moonlit glint off the Thames as a guide into central London during night raids, the forts' main task was to destroy mine-sowing German aircraft plying the English Channel.
During the war, German warplanes created havoc with English shipping by dropping magnetic sea mines from airplanes. The campaign caused the destruction of more than 100 ships with thousands of casualties.
Today the waters of the Thames Estuary around the Red Sands Forts are more likely to get visits from German tourists than German warplanes.
Alan Harmer, part of Project Redsands, the registered charity that maintains the site, said interest for charter tours of the forts from German and Japanese tourists was particularly strong.
"Last weekend it was mostly Japanese and German tourists on board because it had been featured on Japanese and German television recently," Harmer told CNN.
"We've always had ideas to turn it into some type of accommodation and while this latest proposal seems a bit extreme -- I'm not sure it will turn out exactly as proposed -- it's always been something we've had on the cards. It seems the world is interested in these forts."
Peter Shadbolt is a freelance writer who has worked across media platforms in places as diverse as Hong Kong, Italy and the Czech Republic. He now resides in London where he covers science and technology at CNN.com.