A warship sunk by a U-boat attack during the Second World War has been found in the seabed off Northern Ireland.

A team of divers led by underwater explorer and maritime historian Ian Lawler located HMS Hurst Castle while filming BBC One series Dive WW2: Our Secret History.

A Castle-class corvette, HMS Hurst Castle served as a convoy escort during the Second World War. She played a part in the battle of the Atlantic for the Allies, before being sunk by the German submarine U482 on 1 September 1944 with the loss of 17 crew.

Lawler’s divers suspected they had found the warship in October 2011, as a result of a unique map compiled by the historian which he believes charts the locations of many of the lost wrecks of the battle of the Atlantic.

The team carried out two dives, in late 2011 and summer 2012, and the wreck has now been confirmed as that of HMS Hurst Castle.

In Sunday’s episode of Dive WW2: Our Secret History, the divers revealed how the flattened warship was discovered 50 miles north-west of Derry.

She is located 90 metres underwater and rises only 1.5 metres off the seabed. Her stern is missing due to the effects of the torpedo strike, but her main armament, a three-barrelled mortar that fired charges ahead of the ship, a so-called ‘squid launcher’, remains intact.

Lawler told historyextra: “HMS Hurst Castle is the missing piece of the first patrol of U482, one of the most successful by a U-boat late in the war.

“You are trying to explore the history of what happened in that period, and you know the ship has to be out there, so it’s just magic to find her.

“As divers you never know what you are going to find, and you learn not to expect or presuppose what might be down there.

“You could spend lots of time looking for something, but really you are more likely to stumble upon it by just being methodical.”

The BBC One series Dive WW2: Our Secret History sees Lawler’s team of deep-water divers search the seabed off Northern Ireland for the lost wrecks of the battle of the Atlantic.

The battle was one of the longest naval campaigns in history – 100,000 men died and 4,000 ships were sunk.

Presented by historian Jules Hudson, the programme follows the team as they discover the vital role played by the city of Derry in securing Allied victory.

The second and final episode next Sunday will see the team explore the wrecks of three deadly U-boats that once prowled the shipping lanes off Northern Ireland.

The human cost of the battle will also be revealed, when local ex-nurse Lexi Edgar shares a logbook detailing the more than 3,000 injured men he and his colleagues treated in the city.

To find out more about the programme, click here.