Experts have warned an integral part of South Wales’ heritage could be lost for good if Flat Holm Island is “hived off” by Cardiff council.
Money-saving plans to sell off the 86-acre island, revealed by the Labour-run council last week, have met with strong opposition.
James Edwards, a heritage specialist at Colliers International, said it was vital the island was retained by a public body.
“It is impossible to know what would happen if the island was sold into private ownership. Public access could be lost for ever,” he said.
“The coastline around Wales is dotted with small but historically and environmentally significant islands and it is vital the public retains the right to visit and study them.”
Flat Holm currently attracts around 2,000 visitors every year, but the council is proposing to stop visits and sell the island to cut the £150,000 annual running costs.
Mr Edwards added it would be a loss for the people of South Wales.
“It would be a terrible loss if Flat Holm was hived off and ceased to be an attraction for the general public,” he said.
“It is probably a case of not knowing the value of what you have got until it is gone.
“The history contained on this one island is huge and there is a risk that in private ownership, this may be lost to the wider public.”
During its rich history, Flat Holm has been visited by Vikings and Saxons and was also garrisoned during World War II.
Rare plants, such as rock sea-lavender and wild leek, thrive in the unique eco-system and have helped the island to win Site of Special Scientific Interest status. It also has a large population of gulls.
Members of the Flat Holm Society, who have launched a campaign to save the island, also hope a public body will step forward to save the day.
Chairwoman of Flat Holm Society Glynis Parsons said she hoped to follow the example of nearby Steepholm Island, which is owned by a charitable trust.
“It is my understanding that the council does not want to sell the island, but they simply cannot afford the running costs,” she said.
“I think the best scenario would be to approach a charitable trust. We do not want the public to lose access.”
Lundy, the largest island in the Bristol Channel, is owned by the National Trust and managed by the Landmark Trust.
Katherine Oakes from the Landmark Trust said: “The islands of Lundy and Flat Holm are both places of great beauty with abundant wildlife, heritage and history.
“We understand the difficulties associated with running an island and hope a solution can be found for the future of Flat Holm to ensure public access to this magical place can continue.”
Kenneth Smith, of the National Trust in Wales, said the organisation did not currently have plans to buy the island.
“It is not on our radar at the moment,” he said.