The proposed site is only a few hundred yards from the centre of Towcester and is classified by English Heritage as a park of special historic interest.
The water-meadows stretch north from Towcester and, for many, provide the finest view of Easton Neston, Lord Hesketh's 5,000-acre estate, which includes Towcester racecourse. The present house, one of the finest in England, was begun by Sir Christopher Wren in 1692 and completed by his pupil, Nicholas Hawksmoor, in 1702.
But views of the estate could soon be replaced with tarmac and shopping trolleys. South Northamptonshire council supports the proposal for the Safeway supermarket which will include parking for 580 cars. Work could start next year.
English Heritage and the archaeology department at Northamptonshire county council have objected to the plan, saying that it will blight the town and countryside and destroy an important historic site. The remains of an Iron Age cemetery and a Roman settlement have been found there.
However, the district council has included the supermarket development in its local plan, which will now go to consultation before it is considered again. If the council grants planning permission, only the Secretary of State for the Environment could prevent the development. In return for planning permission, the developers will provide about pounds 1m of 'community benefits' for Towcester. These include extra car-parking spaces, refurbishment of a rundown part of the town and the renovation of Bury Motte - the site of a Norman castle, presently overgrown, which will be reopened as an attraction. This week the council is expected to sign an agreement with the developers which will guarantee these benefits.
Phil Leggett, assistant chief planning officer, said: 'In some people's views we are desecrating a famous landscape by building a supermarket on a historic site. Against that we have to balance the advantages the town will gain in the form of better parking and shopping. The conservationists have a point but we see it tilted slightly towards the community rather than the environment.'
Two other proposals have been made for smaller supermarkets, one at a site in the town, the other just outside, but neither is expected to be granted planning permission.
Towcester lies in a prosperous area on the northern edge of the London commuter belt. It has a population of 6,000, with a catchment area of about 25,000, and is expected to grow rapidly. There are mixed feelings within the community as to whether environmental factors should take second place to economic ones.
Alan Hannan, county archaeologist with Northamptonshire council, said: 'It seems a travesty that a beautiful landscape that has evolved over hundreds of years should have to give way to a pile of concrete.
'Towcester is an extraordinary setting - a historic town facing beautiful parkland - which would be ruined.'
An English Heritage spokeswoman said: 'We strongly object to the supermarket. It would have an extremely damaging impact on the historic town, its archaeology, views and the landscaped park.'
Towcester's local history society has called for an investigation of the site before any decisions are made.
Lord Hesketh, 42, a hereditary peer, was a junior minister at the Department of the Environment from 1989 to 1990, a post which later became part of the Heritage portfolio. He then became a Minister in the Department of Trade and Industry and was made Chief Whip in the Lords last year.
It is not known how much Lord Hesketh stands to make from the sale. He said he believed that the community benefits of the supermarket scheme overrode any environmental disadvantages. The water-meadow, he said, was not a particularly beautiful part of the estate and nothing historically 'substantive' had been found there.
He added: 'There's nowhere else in the area you can build a car park. I believe as a whole the net effect of the development will be beneficial.'