The mystery of a shipwreck off the coast of Ireland has been solved 250 years after it sank.

The skeletal remains of the large vessel on Streedagh Strand in Co Sligo, known locally as the Butter Boat, become visible at low tide as the sands shift.

It is a well-known landmark and a popular tourist attraction but its origin was not known.

It had been thought to be part of the fabled Spanish Armada in the 16th century but, thanks to new archaeological and archival research by Ireland’s National Monuments Service, that theory was ruled out and the true identity of the ship has been uncovered.

Samples from timbers off the shipwreck place the construction of the vessel firmly in the first half of the 18th century, some time after 1712.

They also indicated the timber was probably sourced from the English Midlands, possibly Yorkshire.

Further research into 18th century historical accounts led to the vessel being identified as the Greyhound, a coastal trading ship out of Whitby port in Yorkshire in England, owned by a Mrs Allely.

Twenty people died when it sank on the night of December 12 1770.

The Greyhound was caught in a storm off the coast of Mayo and, unable to seek safe harbour in Broadhaven Bay, it was driven to anchor in a perilous position beneath the towering cliffs off Erris Head.

The crew was forced to abandon ship.

But in a tragic oversight, a cabin boy was left on board.

On learning of the plight of the cabin boy, some crew members, the crew of a passing ship, Mary from Galway, and local volunteers from Broadhaven Bay attempted to rescue the boy and the stricken ship.

While the rescue team did manage to board the Greyhound and move the vessel away from the cliffs, the ship was driven further out to sea by the force of the storm with some of the volunteer crew and the cabin boy still on board.

Later that night, she was wrecked at Streedagh Strand, 100 kilometres to the east, with the loss of 20 lives.

Just one man – a Mr Williams “from Erris” – survived the wrecking.

Last Saturday, December 12, the 250th anniversary of the event, locals and members of the National Monuments team who uncovered the story held a ceremony on Streedagh Strand to pay tribute to those who died.

Minister of state for heritage at the Department of Housing, Malcolm Noonan, welcomed the uncovering of the full and tragic story of the Greyhound and the events that led to its loss 250 years ago.

Mr Noonan said there had been a huge amount of local interest in the wreck and he was very pleased that the National Monuments Service had been able to finally confirm the wreck’s identity, adding the use of scientific data and local stories, passed down through generations, bore fruit.

“In particular I am struck by the value of folklore archives along with applied archaeological research in uncovering the full and tragic story of the Greyhound and those caught up in the tragedy,” he said.

“Its calamitous story illustrates starkly the perils of the sea but also highlights how in times of trouble, the common bond of the sea brings people from different backgrounds together in an attempt to save lives.

“I am proud that my department has been able to bring to light this story of tragedy and loss but also of extraordinary bravery, compassion, selflessness and heroism.”