Campaigners hope a planning victory can save a popular beauty spot from proposals to let it flood.

Cuckmere Estuary, near Seaford, is threatened by plans to remove sea defences.

But Nigel Newton, whose home overlooks the nature reserve, has successfully applied to raise the chalk banks of the low-lying plain by 30cm.

Wealden District Council approved the plan, which gives Mr Newton the right to raise the banks if the owners of the rest of the land, the National Trust and East Sussex County Council, agree.

Mr Newton believes if they do, the estuary could be protected for another 50 years.

More than 350,000 people visit Cuckmere Estuary each year but environment managers think saving it would be a waste of money and want to leave it to the fate of the rising sea. Removing flood defences would allow sea water to flood the land, leaving homes which look out on to the nature reserve in the middle of a muddy plain.

Mr Newton, whose company Bloomsbury Books publishes the Harry Potter series, made his application as a protest against the Environment Agency's plans.

If sea water is allowed in, the area would return to marshland, which the agency argues is a more natural state and beneficial to a greater range of wildlife.

Mr Newton believes the tourist attraction would be ruined.

Alan Edgar, who prepared the application for him, said: "In the teeth of huge opposition from technocrats in the Government's quangos we've won a great victory for local people.

"Their plan is to flood the Cuckmere Valley and make it mud flats. We get 350,000 visitors a year and mud flats would not cut it. Businesses would be ruined.

"This plan could hold back the waters for 50 years for just over £1 million."

A similar application will now be discussed by Lewes District Council as the estuary also falls within its boundaries.

If passed, the National Trust and East Sussex County Council would decide whether to finance the build.

Andrew Gilham, flood risk manager from the Environment Agency, was surprised the first application to save the man-made estuary was approved.

The agency said maintaining the defences would cost millions. Mr Gilham said: "This is really a fossilised relic of an old river system and as such it offers only limited benefit for wildlife in its current form.

"Water hasn't flowed through the estuary for more than 200 years, leaving it isolated from the river and heavily silted.

"It would be incredibly difficult to maintain the defences with sea-level rise and climate change."

The agency will present a report expected to recommend removing the estuary's crumbling banks to the flood defence committee in the autumn.

Mr Edgar said Mr Newton's plans represented a "low-key, low-cost alternative".

Eastbourne MP Nigel Waterson has repeated his call for a public enquiry in the hope the tourist spot can be saved. He said: "The defences are already crumbling so we need to get on with any plan they may come up with before it's too late. Time is of the essence.

"The Environment Agency has the view we should let nature take its course. I don't know if they are right or wrong but their argument should be tested. Once we've allowed the meanders to flood we'll completely lose that habitat for ever."

Lewes District Council said its planning decision would not be affected by Wealden's approval to raise 600 metres of the estuary's banks.

An East Sussex County Council spokesman said: "We have not yet received formal notification from Wealden District Council about the granting of planning permission. We will look at the details and consider our position."