A major highway, the A33, would be ripped up and turned back into countryside as compensation for the loss of Twyford Down, the unspoilt chalk hill near Winchester bisected by the M3 in 1992.
But now, say local campaigners, the Government and two local councils are reneging on their "world first" pledge to transform a four-lane road into open grassland for public recreation and amenity - and they are mounting a High Court action to force the Government to keep its word.
At present, the stretch of the old A33 has gone and in its place is a country walk full of wild flowers. The tarmac, diesel fumes and traffic jams have been replaced by a riot of vetches, ox-eye daisies, wild marjoram and purple flowering self-heal.
But a 428-space park-and-ride car park will soon be under construction on a four-acre stretch of the land, complete with toilets, 100 lampposts, administrative building, roundabout and slip roads to junction 10 of the M3. The site extends across the old bypass into the East Hampshire Area of Outstanding Natural Beauty.
Permission to build it has been given by the Deputy Prime Minister, John Prescott, in spite of comments by the inspector at a public inquiry into the plans that local people "regard the undertaking as a pledge to keep the restored former bypass in perpetuity as an open grassed area".
They would regard approving the car park as "reneging on such a pledge", the inspector said.
Now, half a dozen local community groups, organised as the Winchester Meadows Conservation Alliance, which regard the car park as a betrayal, are going to court to fight it.
The original promise came in 1992 from Malcolm Rifkind, transport secretary at the time, who assured Parliament that to compensate the citizens of Winchester for the loss of Twyford Down, the old A33 just east of the city, which until the motorway was built carried the through traffic, would "revert to green fields". His cabinet colleague Cecil Parkinson described the restoration as "a measure of the importance we attach to the environment around Winchester".
Hampshire County Council and Winchester City Council, backed by Mr Prescott and his Department of the Environment, Transport and the Regions, now have other ideas.
"We want more people to use park-and-ride rather than drive into the city centre, and this is a key means to try [to] reduce congestion in Winchester," said a county council spokesman. "We estimate the park-and- ride extension will remove 200,000 car journeys a year from the city centre and that is why we need it."
The campaigners do not agree. Winchester's existing car parks are far from full, they say. On a weekday afternoon last week, the existing 200- space St Catherine's park- and-ride next to the site was half empty. In another car park, only 30 out of 80 spaces were taken. "There's always at least 800 spare parking spaces in Winchester," says Keith Story, chairman of the campaigners. "This is what makes the scheme so very odd."
It is strange, they say, that the county council already owns a site large enough to accommodate the car park - an old depot right next to the restored grassland site, screened by mature trees and entirely within Winchester's development envelope.
He suspects that the whole plan may have a hidden agenda: to provide parking for a so-far-undisclosed high-intensity development on the county council depot site, further increasing its value. "There are so many alternative brownfield sites they could have used for a park-and-ride and have chosen not to," he says.
Alan Weeks, chairman of the Winchester City Residents' Association, said the area was part of Winchester's unique landscape setting. "We would like to see it enhanced so it becomes a great visual and recreational amenity and a significant wildlife resource," he said. "Instead we are faced with the imminent sterilisation of this big stretch of land which has only just been brought back to life."
Last week, Mr Story applied to the High Court for a judicial review of the Government's decision to sell the land to Hampshire County Council.
A spokesman for Mr Prescott said: "Neither Cecil Parkinson nor Malcolm Rifkind made statements which were legally binding. Their statements were fully considered by John Prescott when he came to make the decision in the park-and-ride scheme and were weighed in the balance; and he decided they were not of sufficient weight to cause him to refuse permission."
Mr Story said: "I am sure the whole thing is driven by money. But we believe the people and the environment of Winchester should come first."