Historic England opposes plans for new Cambridge flats
Historic England has opposed plans to build 87 retirement flats in the grounds of a 17th Century country house.
Anstey Hall in Cambridge is a Grade II listed building which is currently used as a hotel and wedding venue.
Historic England said the flats would "encroach" on the open space.
In a planning statement, Trumpington Investments Ltd said: "This planning application provides a once in a lifetime opportunity."
Cambridge City councillors are expected to consider the application at a planning committee meeting next week.
Two three-storey buildings containing 87 two-bedroom retirement flats will be built if the plans are approved.
Trumpington Investments Ltd said it wanted to turn the private space into a high quality, architecturally-led public space for generations to enjoy, adding there would be "tremendous benefits" from the proposals.
The retirement accommodation would provide "easy access to services and facilities on foot and short travel times into Cambridge", it added.
Historic England said the development would "encroach into one of the only surviving elements of the historic grounds which continue to contribute to the significance of the Hall".
"The proximity of the proposed large residential blocks and their contextually inappropriate design would compromise the appreciation of the Hall in what survives of its open setting," it said.
In papers published ahead of the city council planning committee meeting next week, planning officers have recommended the application is refused.
The report said: "Whilst the proposal would provide retirement accommodation for an ageing population, the proposed retirement blocks would consume a substantial portion of protected open space which would not be satisfactorily replaced in terms of quantity elsewhere."
Find BBC News: East of England on Facebook, Instagram and Twitter. If you have a story suggestion email [email protected]