Normally that would be good news, but the park is such a peculiar place that local conservationists who already have a hand in looking after it are afraid that its special qualities may be destroyed by any change of ownership.
The valley is deep, narrow and three miles long; it is also heavily wooded, with trees cloaking its steep flanks and crowding down to the shores of four artificial lakes, which lie in a chain along the bottom. For various historical reasons there are no public rights of way through it, and only a single gravel track meanders from one end to the other.
Anyone walking down that stony road quickly gains the impression of descending into another world, and also into the past, so strong is the sense of isolation that the terrain induces.
The jewel of the valley, enhancing its other-worldliness, is the Mansion, an extraordinary Gothic building, bristling with gargoyles, which was begun in 1854, abandoned in 1868, and never completed. After a long period of neglect, the gaunt stone skeleton of a house was bought in 1988 by Stroud District Council, which leased it for pounds 1 a year to a group of local enthusiasts, the Woodchester Mansion Trust.
Over the past five years this group, now a registered charity, has done wonders in halting the decay which was threatening to destroy the building, and in opening it to the public on a limited scale.
Last year alone volunteers raised pounds 25,000 in subscriptions, visitors' fees and sales through a small shop, and an ambitious programme of restoration has begun. The long- term aim is to stabilise the Mansion in its present incomplete state, and use it as a centre for training in skills such as architecture, stone masonry and conservation.
The policy of the management group has been to keep disturbance of the valley to a minimum: the Mansion is open only on advertised days, and visitors are required to leave their cars in a public park on the main road at the head of the valley, three-quarters of a mile west of the house. A minibus ferries disabled people, but others are asked to walk.
At the site itself, every care has been taken not to disturb the resident colony of greater horseshoe bats, which live in the old brewery at the back of the house and in various roof spaces. These rare creatures have been studied intensively for 40 years by Stephen Ransome, a local schoolteacher now retired, and are of the highest interest to English Nature.
Although there has been activity in and around the house, and between the house and the upper end of the valley, the lower two miles have remained unvisited, except by members of a fishing club which holds the rights on the lakes; and it is hardly surprising that after making such efforts to save the house and preserve the valley intact, members of the mansion group have developed a proprietorial attitude towards the whole property.
When, towards the end of last year, a spokesman of the National Trust appeared on television saying that his organisation hoped to buy the park and open it to the public, perhaps allowing access to pedestrians, riders and bicyclists, local people took offence at the fact that they had not been consulted. Since then alarmist ideas have run riot: the National Trust is going to ruin a unique environment by building a car-park and allowing vehicles down into the valley; the trust is trying to raise money towards the purchase price by making promises to organisations such as the Mountain Bike Federation and the British Horse Society; the trust, in fact, has a hidden agenda, which is to take over the Mansion and run the whole of Woodchester to its own tune.
All this is nonsense. The trust's regional director for the Severn area, Cecil Pearse, emphasises that rumour has run miles ahead of fact.
He points out that the trust has by no means bought the property yet. The asking price is pounds 500,000, and there is a shortfall in available funds of some pounds 200,000. The trust hopes that Stroud District Council, which already makes a handsome annual contribution of pounds 20,000 towards the upkeep of the Mansion, will contribute.
But the purchase will not go through at all unless a suitable site for a car-park can be found and arrangements for safe access agreed with the highway authority - no easy matter, given the awkward, constricted nature of the terrain.
The trust does not have the slightest intention of taking over the Mansion. As Mr Pearse puts it: 'That's the last thing we want. We're entirely happy with the present arrangement.'
On the other hand, the trust does consider the valley worth preserving for the nation, and is driven by its own constitutional obligation - if it manages to become the owner - to give at least some of the nation a chance to see it.
One major snag lies in the fact that for the past 40 years a field study centre has flourished at the Cottage, a house poised on the lip of the valley above the Mansion: many thousands of students from schools and universities have benefited from the chance to work in an undisturbed environment.
The founder of the centre, the late Reginald Kelly, made heroic personal efforts to preserve the Mansion, not only ascending tall ladders to clean out the gutters, but also charging down from his eyrie armed with a shotgun to drive out intruders. His widow, Miriam, still lives in the Cottage, and the centre is going strong; but those who run it are afraid that their patch is about to be ruined for serious study.
Another complication lies in the work of the Ministry of Agriculture, which for the past 15 years has been using Woodchester as the scene of its main badger research project. Partly because of its seclusion, the valley contains the highest density of badgers known anywhere in the world: there are about 200 in the park, and 300 in the study area as a whole. Many are fitted with radio-collars or ear-tags, and ministry staff have put in thousands of hours tracking them to establish their territories and patterns of activity - the aim being to discover whether or not they transmit tuberculosis to cattle, and if so, how.
At a meeting on Wednesday, representatives of the National Trust met officers of Stroud District Council and members of the Mansion group, but a tough, three-hour discussion failed to resolve all the outstanding problems. The thorniest is that of a car-park. The trust hopes it may be possible to tuck one away among the trees near the upper end of the valley, but to the locals even this would constitute an intolerable invasion.
Woodchester raises in sharp relief the question of what the countryside is for.
Is there any justification in keeping humans out of one Cotswold valley indefinitely? Is there any point in preserving the woods and lakes if nobody is allowed to enjoy them?Reuse content