Published: 06:00, 24 August 2019
In an era when the wreck of the Titanic - lying nearly three miles under the freezing waters of the Atlantic - has been extensively filmed and relics retrieved from its deep sea grave, it may come as something of a surprise that a far smaller, and infinitely more dangerous, vessel lying a little over a mile off the Kent coast remains so much of an unexplored mystery.
The wreck of the SS Richard Montgomery - laden with tonnes of explosives - is certainly widely known.
Rife with tales of impending disaster if an explosion was triggered - sparking, some suggest, a tsunami and devastating buildings on nearby Sheerness - it has often become more an amusing discussion topic than a potential death trap; a peril we have lived with and collectively crossed our fingers over.
Yet precisely 75 years since it sank off the coast of Sheppey, a lack of knowledge as to its true condition and load, coupled with what appears to be a masterclass in political apathy, has meant any opportunity to recover it and make the area safe remains a concept which is kicked down the road like the proverbial can.
A recent debate in the House of Lords started with a call for action, and ended with many peers agreeing it was "best leaving well alone".
Local MP Gordon Henderson earlier this summer continued to back the "non-intervention" policy supported by countless governments when it came to just what should be done.
It is a situation which has frustrated many.
Among them is David Alexander, professor of risk and disaster reduction at the University College London.
An expert in the field, he has recently penned a report into his extensive research into the Montgomery after trawling the National Archives for information.
"The whole business is completely bizarre that they have left it all this time," he explains.
"There's a sense among so many people who don't understand the situation, that if you leave bombs long enough they neutralise themselves but I just don't think that's true.
"I was scandalised by that debate in the Lords. They were obviously trying to head off any attempt at a serious discussion. It was grossly embarrassing.
"Toby Harris (Labour peer Baron Harris of Haringey), who I got interested in the issue over dinner, raised it as he's genuinely very concerned about it, and would like to see something done, however, it was clear from the start stonewalling was what they intended to do.
"Not so long ago a half tonne war time bomb was found next to the railway at Milan central station - it led to 50,000 evacuees, the main train station and all routes around it shut for 36 hours as they removed it, and that was just one bomb. The Montgomery is full of them - hundreds and hundreds of them."
An annual survey is conducted providing computer images of the state of the wreck, but the truth remains no one is certain of just how much of its cargo remains down there, amid concerns shifting sands could actually be moving bombs from the boat across a wider area. In addition, the wreck is potentially so fragile the slightest movement of any exploratory dive could trigger a catastrophe.
Professor Alexander adds: "So much has been written about this decidedly strange tale, but the resultant body of literature is rife with distortion, misestimation, speculation and exaggeration."
The best estimates suggest there remain 13,500 bombs packing an overall total of 1,434 tonnes of TNT.
Estimates some years ago put the cost of clearing the wreck at £40 million - a figure now likely to be multiplied many times over with any attempt coming with a profound sense of danger.
Professor Alexander says of some of the suggestions put forward: "Controlled detonation of the cargo is out of the question.
"To build a sarcophagus, Chernobyl-style, over the wreck would probably cause structural collapse onto the bomb-racks. Similarly, to build an 1,800-metre-long coﬀer dam around the wreck would disturb the stability of the ship's superstructure.
"On the other hand, extracting the bombs and making them safe would take at least six months and would, following normal procedures, necessitate the evacuation during all of that time of about 40,000 people. It would be a hazardous occupation that would require diﬀerent techniques for diﬀerent kinds of bomb.
"In the case of the Richard Montgomery, the level of uncertainty virtually precludes any kind of rigorous assessment of risk, which would be a necessary ﬁrst step in determining the right course of action to govern it."
Today an exclusion zone surrounds the wreck - its masts still clearly visible emerging from the water. So just what is the danger it now poses - when even the last survivors of the conflict it dates from are fast diminishing in number?
"The worst case scenario," says the professor, "is very difficult to predict as the official evidence is completely contradictory. One study in 1970 said it all going up wouldn't do much other than break a few windows in Sheerness,which I find difficult to understand.
"It would be an underwater explosion - albeit a very shallow one. Would that generate a tsunami or would the water act as a barrier and mitigate the blast?
"The other scenario is a 3,000 metre high column of water, debris, sand and steel, and a five metre tsunami which would then wash across Grain.
"If that were to happen, tsunamis are capable of catching fire.
"After the Japanese earthquake the entire coast was on fire after the tsunami because oil caught fire and then floats on the water, while still ablaze.
"If that went up the Thames goodness knows what would happen."
Just what is the SS Richard Montgomery?
Built in Florida, it was one of a number of cargo vessels built in the US during the Second World War.
Designed to be simple and cost-effective to construct, the shortcuts in their creation saw hull plating welded rather than riveted - a process which would prove key to the Montgomery's destiny.
Launched in 1943, she had been put straight into service, crossing the Atlantic to Liverpool.
But it was in August 1944 she would begin her fateful journey.
Loaded with 6,225 tonnes of high explosive bombs and detonators in Philadelphia, she set sail to Cherbourg to meet with the US Air Force.
First, though, she was to join an Allied convoy en route, in the Thames Estuary.
Upon arrival, she was ordered to berth off Sheerness but on August 20, 1944, dragged anchor and ran aground on a sandbank. As the tide receded she broke her back around 1.5 miles from Sheerness. The crew, made aware of the ship's perilous state by the loud noise of its hull giving way, all escaped unharmed.
A salvage operation took place days later, but the ship's hull cracked open and areas became flooded. A month later the effort was abandoned due to the danger it posed. It subsequently broke into two.
It has been left untouched ever since, lying in around seven metres of water.
Did you know?
The Montgomery was declared an official secret by the government up until the 1950s - despite widespread awareness of its existence.
The US government owns the wreck and made two attempts to offer assistance more than 40 years ago - but both offers were refused by our government for reasons lost in the mists of time.
In 1999 an official risk assessment was conducted by the government into the wreck - it remains a classified, secret, document.
A key stumbling block for the 'Boris Island' airport idea, touted by the now Prime Minister Boris Johnson on Grain, is believed to have been the enormous cost of clearing the Montgomery.
In 1964 experts blew up the SS Kielce munitions ship off the coast of Folkestone.
Around 100 tonnes of explosive went up causing a magnitude 4.5 earthquake and 47-metre long, six-metre deep crater in the sea bed and a 150-metre high column of water - damaging buildings in the town.
The Montgomery has ten times that amount.
Over 40 cases have been reported of flames on the water around the wreck, caused by phosphorus leaking from bombs and catching fire when it reaches the surface. They are not thought to pose a threat to the munitions on board.
More by this authorChris Britcher