Winston Churchill might have vowed to “fight them on the beaches” but Britain’s Second World War prime minister obviously never planned to do battle at Leysdown.

The new owners of Central Beach Holiday Park have caused fury at the eastern end of the isle of Sheppey after barricading off a section of the sand.

Resident Elizabeth Chandler fumed: “I am shocked this has been allowed. As of Thursday no one is allowed to walk on this part of the beach. All steps have been blocked and fenced off.”

Pat Sandle, who chairs Leysdown parish council, warned: “They will never be able to enforce it. The public has a right of access.”

To prove her point, families continued to stroll along the beach at the weekend oblivious of the new sign which announced:

“Please take notice. Beyond this point is private property. No motorcycles. No horses. No public right of way.”

Social media exploded with indignation as Facebook members insisted Cosgrove Leisure Parks, which bought the 17-acre caravan site from Maureen Wharton in the summer, had no legal right to close the area.

One insisted: “No one owns the coastline. It is for all the public.”

Another said: “No one owns no part of any beach on this Island at all. If they have done this, it is against the law, my solicitor told me.”

But Swale council has confirmed that part of the beach is privately owned, although a spokesman admitted the public could walk on the sand below the high water mark.

Cosgrove’s operations manager Andy Johnstone defended the move and said it was part of a £500,000 investment over the next 18 months. He said: “There has been a lot of vandalism with unruly behaviour there.

“Caravans have been burned out, rubbish has been dumped and motorbikes and quad bikes have been ridden all over the place.”

And he insisted: “We are staying within all legal requirements and have been working closely with the local authority. We are not in the game of breaking any rules.

“There is a public right of way along the top of the beach and we have not touched that.”

He added: “No one has contacted us directly although I am aware of the comments on Facebook. We are trying to tidy this part of the beach up. Over the years it has been unloved and allowed to become unkempt.

“We want it to be an asset for Sheppey, not a dumping ground. We have plans to landscape some of the land and have already begun planting palm trees to turn it into a nice area."

Cosgrove Leisure is a family-run firm with three generations from Paddy Cosgrove to his son Patrick and grandson Paddy Junior. It also owns Sheerness Holiday Park and is redeveloping a park for lodges in Chertsey on the banks of the Thames.

When director Paddy Cosgrove bought Central Beach he promised: “We will invest time and effort to transform Central Beach while retaining the strong family values Maureen established in her 40 years ownership.

“In the fullness of time Central Beach will raise the standards of holiday parks on the Island to the benefit of all.”

Generally, the seabed and foreshore belong to the Crown. But sometimes the Crown has given it away. Large parts of The Swale belonged to the Lees Court Estate which transferred it to an offshore company.

In Whitstable across the water from Leysdown the Whitstable Oyster Fisheries Company controversially owns part of the beach.