Allotment holders fighting plans by the Duke of Northumberland to build homes on their plots have succeeded in getting the land listed.
getwestlondon reported last November how the owner of Syon Park, Ralph Percy, wants to build 120 homes on Park Road Allotments, across the road from the estate in Isleworth.
The land is owned by the duke but has been used as council allotments for a century, and gardeners opposed to the move have described it as a haven for rare birds and other wildlife.
The Isleworth Society's application for the site to be listed as an Asset of Community Value has now been approved by Hounslow Council.
The protected status would give members of the community six months in which to prepare a bid should the land be put up for sale.
However, it does not affect the duke's plans to retain the land and rent out the homes to fund the upkeep of his estate.
The council recognised in its approval letter the "strong local support" for the listing and that the current use of the land "furthers the social wellbeing and social interests of the local community".
The letter states the duke's estate objected to the application for the land to be listed, partly on the grounds that the land is connected to a residence.
However, the council's letter states: "Although the land is part of the Syon House Estate it has no direct connection to an existing residence as evidenced by the fact that from 1914 until very recently it was leased off as allotments."
Christine Diwell, of the Isleworth Society, said: "While of course this only provides limited cover in the event of a sale of the land which we know at present is not contemplated, it's clear from the reasons given for approval that Syon Estate objected to the application so nothing as far as their future plans can be discounted. Syon Estate do of course have a right of appeal."
"This does not impact on the plans"
The duke's estate, which has yet to submit a planning application for the proposed new homes, has offered existing allotment holders an alternative site within the grounds of Syon Park. It said the majority of them had agreed to take up the offer.
It claims the proposed homes have been sensitively designed and would provide much-needed local housing while financing the maintenance of the grade I-listed Syon House.
A spokesman for the Northumberland Estate said: "We note the decision of the council in respect of the designation.
"This does not impact on the plans for the Estate to seek to relocate the allotments and to make use of the land for rented homes.
"We are continuing to meet all local interested parties to discuss the proposals prior to the submission of a planning application."
"Worth fighting for"
The land is understood to have been used as an allotment site since at least 1914. It was previously leased to Hounslow Council but came back under the duke's management in 2015.
There are 37 allotments, and plot holders have a tenancy agreement in place until March this year.
The new allotments offered within Syon Park have been criticised by some existing plot holders as "sterile" and "designed by architects to be as anti-allotmenteering as is possible".
A website set up by campaigners opposing the plans states: "Park Road Allotment site is the last remaining patch of land that is undeveloped: look around you and notice the sites that have been and are being re-developed - light engineering and industry of any kind is being banished from Isleworth.
"Perhaps this little patch of land is worth fighting for; horsetail, bindweed, claggy clay and all."