TODAY marks 71 years since the SS Richard Montgomery sank off the coast of Shoebury taking 1,400 tonnes of explosives with her.

The American Liberty ship ran aground in waters 24ft deep about 1.5 miles from Sheerness and five miles from Shoebury in 1944.

Ever since that day, the thorny issue of what is done about the stricken vessel and her dangerous cargo has remained.

Breaking into two pieces, the Montgomery has lain in the estuary mud since that day.

Today, the masts of the wreck still protrude from the water and the site is cordoned off by warning buoys, but concerns about its structural integrity and fears of its arsenal exploding have been raised for years.

Shoebury councillor Mike Assenheim said: “This pops up from time to time and, with the anniversary of the end of the war, people are probably thinking more about it.

“I’ve asked questions in the past and have always been told it’s safer to leave it as it is because to disturb it could cause problems.

And, if it goes bang, all the windows in Shoebury will break.

“When I try to get information from the Ministry of Defence, they don’t let much out, but it has been a concern for a lot of people on both sides of the estuary.”

The merchant ship was built in 1943 by St John’s River Shipbuilding Company of Jacksonville, Florida, as one of 2,700 Liberty ships produced to carry supplies for the war effort. She was named after an Irish general who died in the American War of Independence.

At the time of her sinking, she had been carrying bombs en route to join a convoy to Cherbourg in France, which had come under Allied control in July of that year during the Battle of Normandy.

She was ordered to berth at the Great Nore Anchorage, off the north edge of Sheerness, by the harbour master at naval control, which was on HMS Leigh, the code name for Southend Pier.

She was dragging her anchor and ran aground on a sandbank.

The water was 24ft deep, but the Montgomery had a draught of 31ft and broke her back as the tide went down.

Desperate attempts were made to salvage the cargo, but by the following day, a crack appeared in the hull and the forward end began to flood. By September 25, only half the cargo had been removed. Once the vessel flooded completely, the salvage operation had to be abandoned, with 1,400 tonnes of explosives remaining in the forward holds.

The wreck was left in two pieces.

Martin Terry, Southend councillor for public protection, said: “Medway Ports is contracted by the Maritime and Coastguard Agency to mark and guard the wreck and ensure shipping avoids the area. The wreck is also under 24-hour radar surveillance by Medway Ports “We understand regular surveys are carried out and the most recent report suggests although the risk of a major explosion is remote, the wreck remains monitored.

“It says the hull is subject to prevailing environmental conditions and is showing evidence of gradual deterioration, but considered to be in a stable condition.

“We would expect to be notified of any developments or changes with this.”

The wreck is considered so dangerous, a paddle boarder was told by the Maritime and Coastguard Agency he faced prosecution for entering the exclusion zone in June, after posting a photo on Facebook of himself in front of the masts.

Concerns were also raised regarding Mayor of London Boris Johnson’s now-sunken dream of building an airport in the Thames Estuary, which it was feared could disrupt the wreck, and an e-petition was started by residents to have the wreck removed.

A report by the Marine and Coastguard Agency in 2011 said the hull was “slowly deteriorating and eventual collapse is inevitable.”

However, the risk of a major explosion is considered to be “remote”.