Mayor of London Boris Johnson’s ambitions to create an airport off the Kent Coast may now be scuppered because a wartime ship containing around 1,400 tonnes of unexploded bombs is rapidly deteriorating.

The SS Richard Montgomery lies on a sandbank in the Thames Estuary. The American Liberty Ship has been there since running aground on 20 August 1944 and is situated in the possible flight path of aircraft which would be flying to and from the proposed airport.

A recent Marine and Coastguard Agency study of the shipwreck has found that some parts of the vessel are deteriorating at an accelerated rate. The Agency said that there was a danger of structural collapse in some areas and also the possibility of munitions escaping from the wreck. The ship contains some 2,000 cases of unexploded cluster bombs.

A report commissioned by Mr Johnson has also raised concerns over the location of the SS Richard Montgomery in relation to the site of the proposed airport development. The Agency admitted that even though there had been some investigations into the stability of the explosives, it could not accurately determine what effects a structural collapse would have on the ship’s cargo.

There is already an exclusion zone marked on shipping charts around the ship. The Marine and Coastguard Agency report suggests that it might be time to rethink the policy of non-intervention with the vessel as the possibility of structural collapse becomes more likely. The Agency is currently considering its options in terms of careful intervention.