The locations of three boats used in the Dunkirk evacuation in the Second World War have been uncovered for the first time by a detailed survey of 30 shipwrecks off the French coast.

More than 338,000 Allied soldiers were rescued by small boats from Dunkirk in nine days between May 26 and June 4 1940.

Now Historic England and its French counterpart, Drassm, have carried out detailed surveys of 30 wrecks showing their position, characteristics and condition in “remarkable detail”.

Historic England chief executive Duncan Wilson said: “It’s very moving to see new details emerge from 30 shipwrecks linked to Operation Dynamo for the first time since the events at Dunkirk during the Second World War.

“We’re pleased that a geophysicist from the UK, commissioned by Historic England, has been integral to the survey that has successfully captured these details alongside Drassm’s incredible team of scientists.

“The results give us a striking insight into our shared heritage that still lies beneath the waters off Dunkirk.”

The main instrument used for the survey was a multi-beam echo-sounder mounted beneath the hull of the Drassm research ship Andre Malraux.

The instrument emits a fan of sound that is recorded as it bounces off the seabed, and the data is used by geophysicists to create a highly detailed three-dimensional image of seabed features such as shipwrecks.

A total of 27 Operation Dynamo wrecks were located and studied, with the precise location of 12 of these not previously known.

Four wrecks, either destroyed or covered by sand, could not be found.

A Historic England spokeswoman said: “A further 19 features have been studied, three of which appear to correspond to the location and characteristics of vessels lost during Operation Dynamo that were previously undiscovered.

“The identities of two wrecks – the French auxiliary minesweepers Denis Papin and Moussaillon sunk by air attacks on June 1 1940 – have been corrected.

“The new data showed that previous identifications had confused the two wrecks.”

The spokeswoman said added that the survey data was detailed enough to confirm the identification of 19 wrecks by matching dimensions and features with historic photographs.

“On one wreck, the davits from which lifeboats once hung can be seen in the survey data. Their precise form – together with other details and dimensions – confirm that it is the Normannia, requisitioned as a troop carrier and sunk by an air attack on 30th May,” she said.

“The survey has confirmed that many of the Dynamo wrecks are in relatively good condition.

“However, the new data also shows recent changes.

“The destroyer HMS Keith was surveyed in 2016 and 2019 by the Port of Dunkirk (Grand Port Maritime de Dunkerque – GPMD). The 2023 survey shows that part of the destroyer’s hull has degraded in just a few years, collapsing away from its former position.”

The survey is the first part of an ongoing project which next year will see local divers carry out further investigations, with the findings to be displayed in museums and online.