Bayard’s Cove Fort is one of six historic castles in England at risk of coastal erosion, a new report has said.

The iconic monument on the River Dart in Dartmouth was built in the early 16th-century to help defend the entrance to the harbour.

But despite having withstood the ravages of time for almost 500 years, the landmark could collapse in less than a century due to the growing threat of coastal erosion, storm surges and sea level rise.

According to the World Climate Research Programme, sea levels are expected to rise by more than one metre by 2100, threatening more than a quarter of the UK’s current flood defences.

The 22-page report by Aggregate Industries (AI) said five other renowned heritage sites were also under threat and “already being heavily impacted”, including Tintagel Castle in Cornwall, and both Hurst and Calshot Castle in Hampshire.

AI, a supplier of construction materials used in the building of coastal defences, said that the castles combined would require more than £275,000 in repairs and sea defences to overcome the threat.

The number of residential properties at risk from coastal erosion is also estimated to increase from about 270 in 2030 to between 1,980 and 4,150 by 2110.

The report warned that tourists “are less likely to return to areas experiencing continued beach erosion”, adding that coastal damages alone “could drive a £12 billion loss to the UK economy”.

In response, the report suggested building wall defences and breakwater islands, stabilising the soil with native vegetation, restoring wetlands, and even relocating buildings and infrastructure as part of a policy of ‘managed retreat’.

It also called on politicians to prioritise coastal erosion risk strategies when planning infrastructure, and for industry to contribute to coastal defence projects.

Lee Sleight, AI’s managing director, warned that land present only 50 years ago had now vanished, adding that the forecasted rise in sea levels painted “a dire picture”.

He said: “Many of the UK’s most iconic landmarks are at risk of not being around for future generations. While the government's commendable commitment of £5.2 billion aims to protect vulnerable locations, the enormity of the challenge demands more.”