THEY were once a common sight around the coastline of Britain.

But the 'exceptionally well-preserved' wreck of a minesweeping trawler off the Purbeck coast is now a rare survivor.

One hundred years ago, however, HMT Arfon and its 13 crew members tragically struck one of the mines they were tasked to sweep.

The vessel sank in under two minutes, killing 10 of the crew, including the vessel’s captain, John Abrams (Royal Naval Reserve) with only three survivors who were blown overboard by the mine’s explosion.

The wreck lay undiscovered for decades until it was found south of St Alban’s Head, near Swanage in 2014 by Martin and Bryan Jones, who run a family dive charter business.

Last year the wreck was afforded special status from the Department for Culture, Media and Sport on the advice of Historic England. It means access to it will be restricted.

Martin and Bryan organised a special commemoration on Sunday, April 30, to mark the centenary of the sinking of the Arfon.

They invited the descendants of three of the crew - John Abrams, second hand Edward Youngs, and cook/deckhand James Doy – to the event.

The commemoration ceremony involved the restored steam whistle, recovered from the wreck of the Arfon. It was sounded for the first time since the sinking in 1917, when it was used to signal the code for ‘MINE.’

The names of the 10 crew that perished were read out in addition to the names of the three survivors. An information board, funded by Historic England, about the Arfon was also unveiled.

According to Historic England, the Arfon was built in 1908 in Goole, East Riding of Yorkshire, for the Peter Steam Trawling Company of Milford in South Wales as a 227-ton steel trawler.

It was requisitioned by the Royal Navy in 1914 and fitted with mine-sweeping apparatus and a deck gun.

These features, as well as the trawler’s portholes and engine room, are still intact on the seabed.

The Arfon worked out of Portland Harbour naval base sweeping mines laid by the UC-class of mine laying U-boats along the inshore shipping lanes off Dorset.

The trawler swept mines for nearly three years before it sank.

The loss occurred during the time of unrestricted submarine warfare by Germany which, from February 1917, saw an increasing number of shipping casualties.

Trawlers were well-suited to their wartime task because they were robust boats designed to work heavy trawls in all types of weather and had large working decks, which easily accommodated a mine sweep.

By the end of 1916 the navy had requisitioned so many trawlers, and the war had such an impact on shipping, that the supply of fish to the UK was limited.

By the end of the war, over 300 British trawlers had been lost through minesweeping, along with half of their crews - a much higher rate of loss than that experienced by troops serving in the Western Front trenches, where the loss rate was approximately 11.5 per cent.

Joe Flatman, head of listing programmes at Historic England, said minesweeping trawlers now survive only in documents and as wrecks like the Arfon.

“The Arfon shipwreck is a rare survivor of a type of vessel once very common around the coastline of Britain but which has now entirely disappeared,” he said.

“Trawlers, minesweepers and other coastal patrol vessels played a crucial role in keeping the sea lanes around the British Isles open during both World Wars, a part of the war effort that is often overlooked.

“The crews who served aboard such vessels faced tremendous dangers with unstinting bravery and devotion to duty. Historic England is proud to help tell part of this hidden story of naval endeavour during the First World War as part of our work.”

The organisation has recently revealed a new virtual dive trail it has created of the Arfon wreck, which can be explored by visiting cloudtour.tv/arfon.

Fishing vessels of this date are rarely, if ever, archaeologically investigated according to Historic England. Most of the wrecks around the coast have been salvaged for their fixtures and fittings. The Arfon is unique in that it had been untouched for 100 years so it provides a rare source of information.

It was considered to be vulnerable to souvenir hunters and uncontrolled salvage, which is why it was given special protection under the Protection of Wrecks Act 1973. It means that access to the site is restricted only to divers who have been granted a licence from Historic England.

At the commemoration of the Arfon’s centenary, Martin spoke about working with the relatives of the crew lost on the vessel 100 years ago.

He said: “I have found it enormously rewarding sharing the information with the descendants of three of the crew and meeting them all on the centenary commemoration.

“We would like to thank Historic England and the Maritime Archaeology Trust for the enormous amount of work that they have contributed to this project and we hope the Arfon will be left in its pristine condition and respected for its rarity and historical value for many years to come.”