Experts say a shingle ridge which protects thousands of properties is moving and the future of sea defences on part of Norfolk's coastline may need to be reviewed.
But those who live or stay beside the bank at Snettisham, near King's Lynn are not convinced.
And some are even digging into the structure - prompting warnings they could weaken it and face prosecution.
Tests are being carried out along the bank, which stretches from South of Hunstanton to Wolferton Creek, amid fears the sea is pushing parts of it inland.
If they conclude that a so-called 'trigger point' has been reached, it could prompt a major rethink of the area's sea defences and see many of its caravan sites moved inland.
If anyone at Snettisham was worried about flooding, you'd think it would be Philip Meade.
The retired company director's bungalow stands on the seaward side of the ridge and was devastated by the 2013 storm surge, which left his insurers with a £60,000 repair bill.
"I've been here 11 years and the shingle's come up the beach since then, it's got higher," said Mr Meade, 70, whose family has owned the property since aquiring it for a little over £2,000 in the 1960s.
"I love it here, I really do. We've had a lot of good times here, but we've been flooded as well, in 1978 and 2013.
"Last time it took a year to get it right again. They replaced all the walls but they had a job to get the plaster to dry."
Mr Meade is one of a handful of people who can live full time in their properties, because they were constructed before 1947.
"The Wash is silting up, there's weed growing out there now," he said. "I don't really think they need to do anything to the beach.
"The tide doesn't come up as high as it used to do, if there's a surge nothing can stop it anyway."
Brian Clarke, 71, who bought a caravan inside the shingle six years ago, agreed the estuary was becoming silted up.
"It's got to the point where you can see where the mud is, there used to be a gully out there but that's gone now, it's all gone," he said. "I'd like to see the beach stay as it is."
Another caravan owner was more pragmatic about the flood risk.
"I've got new for old insurance on mine," he shrugged. "So I'm not bothered."
Each spring, shingle washed south down the estuary by winter storms is loaded into lorries and taken a mile or two north to replenish defences at Heacham, where the ridge is visibly eroding.
Along the ridge, some properties have decking which butts against the ridge, while steps and pathways appear to have been dug into it.
A spokesman for the Environment Agency, which maintains the defences, said: "In Heacham and Snettisham, the consequence of the natural evolution of the ridge is that the beach side properties are experiencing an increase in the amount of sand on their property.
"We are engaging and advising residents so that they understand the significance of the ridge and why they should not undertake any further excavation activity. If necessary, we will take enforcement action against property owners that damage the ridge.
"It is important that property owners refrain from digging into the ridge at all and that they approach the Environment Agency if they wish to undertake works within 16m of it. This will help preserve the integrity of the ridge and its ability to perform as a natural flood defence."
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