Conservationists fear for the future of a little-known but historic wall if plans for a roof terrace go ahead.
Their fears have led to calls for the 160-year-old wall to be given “listed” status to give it legal protection.
The Brighton Society said that the wall, between Ventnor Villas and George Street, was made of bungaroosh, cobble, flint and brick.
And the society described it as a “little known but important part of the history of Hove”.
It forms the eastern border of the Cliftonville Conservation Area but is not mentioned in the “character statement” for the area.
Brighton Society chairman Jeremy Mustoe said that there was a general lack of awareness about the historic wall because the George Street side had been rendered so the flints and stones were only visible from the Ventnor Villas side.
He said: “We want to highlight the potential threats to it resulting from existing and future construction work on the George Street side of the wall, particularly as recent planning applications do not appear to include heritage statements which, as the wall is in the Cliftonville Conservation Area, they are required to do.
“This indicates that the planning department probably does not even know about the wall, let alone its extent, its height or its history.”
The application by the Geneva Investment Group, a property company with a multimillion-pound portfolio, owned by Ivor and Matthew Sorokin, is to remove a window and install a window and door to the rear of 29 George Street and add a cedar fence screen.
It has prompted 19 letters of objection to Brighton and Hove City Council from neighbours concerned about loss of privacy, light and more noise.
Ernie Fortnum, whose home backs on to the wall, is concerned that business owners in George Street do not know about the wall’s heritage.
He said: “Workmen innocently drilling into it from their side and hitting embedded flint could do all sorts of damage.”
Labour councillors Clare Moonan and Gary Wilkinson, who represent Central Hove, are backing neighbours in their fight against the plans.
In a joint statement, they said: “This wall is a beautiful and historic structure which is part of the heritage of central Hove and must be protected.
“We will be opposing the planning application as it will change the character and appearance of this wall.
“We are also concerned that the construction will damage the fragile structure. We will work with the council and local heritage bodies to protect the wall in whatever ways we can.”
Save Hove campaigner Valerie Paynter is concerned about the accuracy of character statements for all conservation areas given that the wall is missing from the Cliftonville statement.
She said: “There is no heritage statement with this planning application and wherever surviving flint walls persist planning officers should be automatically looking for and demanding properly prepared heritage statements in case a wider local history story is buried there.
“The development in The Lanes coughed up the building blocked in by centuries of accretions which is now a listed building.
“We must be alert to what needs conservation protection that’s currently overlooked.”
People can look at the plans and comment on them on the council’s website by searching for BH2020/01791 at planningapps.brighton-hove.gov.uk/online-applications.