Belle Tout, a 19th century lighthouse, is in danger of plunging over the chalk cliffs by Beachy Head. Stephen Goodwin reports on one couple's novel attempt to get their precarious home moved 70 feet inland.

Mark and Louise Roberts are praying for unusually calm seas off Sussex this winter. Erosion has brought the edge of the overhanging cliff to within 30ft of their lighthouse. If the south-westerlies which hammer up the English Channel undercut more of the chalk, Belle Tout may not survive.

"It's an eerie experience. You can hear the dull thud as each wave hits the cliff," said Mr Roberts, a former hotelier who moved into the lighthouse a year ago.

The building, with its 45ft lamp tower abutting a two-storeyed house, is a familiar sight to walkers between Beachy Head and Birling Gap. But what is not visible from the path is the extent to which the sea has undercut the 330ft cliff.

Mr Roberts reckons that if a rod was drilled straight down from the lighthouse it would emerge into fresh air above the waves.

"I'm not looking forward to the gales coming through this week at all," he says. "We always keep a wary eye on the weather forecast."

Predicting when more of the cliff might peel away is difficult. It has not eroded at a steady rate but in occasional massive falls.

In 1896, some 80,000 tons of chalk broke off and fell in to the sea. The debris forms a kind of breakwater to be slowly eaten away again.

When Belle Tout was built in 1832, it was 100ft from the cliff edge; by the 1950s the margin was down to 70ft.

The granite building replaced a wooden folly with a working light built by a local MP, "Mad Jack" Fuller, to warn ships plying their way along the Channel away from the great chalk promontory.

But Belle Tout was shrouded in fog so frequently that Trinity House - the body responsible for Britain's network of lighthouses - decommissioned it in 1902, preferring instead a lighthouse at the base of the cliffs - the photogenic Beachy Head light.

During the Second World War, Belle Tout was used for "friendly fire" target practice and since then it has had a succession of tenants including an architect, a novelist and the BBC, all attracted to its dramatic location. The BBC used it as the setting for its 1980s dramatisation of Fay Weldon's Life and Loves of a She Devil.

"At the moment it looks like a toilet block in the middle of nowhere," observed Mr Roberts, who plans to replace the 1950s brick of the upper storey of the cottage with cladding of granite to match the original stone.

But the restoration will not be on the present suspect site. The Roberts have formed a charity - The South Downs Lighthouse Trust - to raise money physically to move Belle Tout out of danger. It will then be open to the public as a museum.

Plans for the move are due to be considered by Eastbourne Council, the concerned landlord. Contractors will dig beneath the whole building, raise it two feet in the air, lower it on to "greased skates" and then with hydraulic rams slide it 70 feet inland to new foundation on an old croquet lawn. If all goes well, the "graceful" journey will take six hours.

The technology exists but the operation will cost in the order of pounds 250,000. Mr Roberts said the Trust would stay in being to preserve maritime history and, one day perhaps, to move Belle Tout to safer ground again.