Confusion surrounding the classification of Medi Parc has left villagers unsure how to oppose plans to build a 400-home care centre on the land.

The site, next to Harefield Hospital, in Hill End Road, is earmarked for development by care company Red and Yellow, which hopes to build a ‘village’ specialising in caring for people with dementia.

The land is in the green belt, so there are many planning hoops for Red and Yellow to jump through.

However, any land that has been developed in the past can also be considered ‘brownfield’ – this has fewer restrictions for which planning approval is usually easier to secure.

Harefield Hospital built temporary hut wards on the land in the early 1900s, and Red and Yellow’s planners argue the site is therefore both brownfield and green belt.

“The two things are compatible,” said Peter Dines, planning agent at Red and Yellow.

In addition, Hillingdon Council policy states the authority will support development at the Medi Parc for any medically-related establishment, and in 1990 it gave permission for a medical research centre and business park, but building never began.

“The council’s policy states that redevelopment for health purposes in the green belt area is acceptable in principle as long as key considerations are met around issues like parking and landscaping,” said Mr Dines.

“The policy also explicitly states that green belt considerations should be taken into account along with compatibility with the Harefield Village Conservation Area, which is something Red and Yellow’s proposals will specifically address.”

Hillingdon Council has not confirmed if planners consider the land brownfield. It said the site is in the green belt, but would only say any applications will be considered in accordance with council planning policy.

Harefield Tenants’ and Residents’ Association (HTRA) intends to continue to fight the plan on the grounds the space – a Site of Special Scientific Interest – should not be developed at all.

Last year, the group lead a battle to stop the owner of the land, Comer Homes, building luxury flats by trying, ultimately unsuccessfully, to designate it as a village green. Since then, Comer has entered a deal with Red and Yellow.

HTRA chairman, Paul Stone, warned people at a meeting on Monday last week that they should be careful about what they oppose, as an alternative could be even less appealing.

“It’s illogical to me that you can build on green belt at all but we have to look at this practically,” he said. “Look what happened in Rickmansworth – they opposed plans to build houses and now they have a Tesco.”

Red and Yellow is finalising plans after a public consultation this month, and expects to file in the new year.