Historic England has objected to proposals for more homes at Felixstowe’s former Bartlet Hospital, claiming the development would harm a building in the top 5.5% of Britain’s best properties.

Conversion of the Bartlet and construction of new homes in its grounds is already creating 36 homes.

The building, contructed on part of a Martello Tower and a prime example of a coastal convalescent home, is a Grade II* listed property. Its grounds also include the remaining part of the Bath Hotel, which was torched by militant suffragettes.

Gipping Homes wants to build an apartment block for three flats plus garaging on a car parking area.

Felixstowe Town Council has recommended approval as it believes the apartments would be too far from the main building to have a major impact, would be sympathetic to the adjacent annexe, and not lead to any overall loss of parking.

Historic England though disagrees strongly and said “the proposed new building would result in harm to the significance of the listed building”.

It “would not support the principle of development in this location as we remain unconvinced that development can be undertaken without causing unjustified harm to the heritage asset”.

Suffolk Coastal planning officers are recommending the planning committee refuse the scheme because it would “encroach upon and erode the open setting” of the listed building.

The council’s senior design and conservation officer, Robert Scrimgeour said: “For me, it is now very straightforward to be able to judge the importance of the space around the Bartlet given that it has now been successfully managed and re-landscaped to reveal the true monumental status of this building (for which all credit to the applicant).

“That is why the development site, regardless of its current use, makes such an important and positive contribution to the setting of the Bartlet in its open and undeveloped form, a character that is established and historic.”

The developers have also offered £50,000 towards provision of an affordable home elsewhere in the town – previously they have said the development will not make enough money to provide affordable homes.