A decision to board up Northdown House, threatened with closure by Thanet council, has been described as a “retrograde step” by dismayed councillors.

The building is one of 15 around Thanet which the authority says are surplus to its requirements.

However, the council must wait until next year to learn whether it can be sold to developers, after a covenant emerged, indicating the property should be for communal use.

Northdown House will now be boarded up when the current lease with Thanet Leisure Force expires in December.

Cllr Clive Hart, who represents the Cliftonville West ward, said: “We will be left with an empty building that will fall into disrepair and eventually become an eyesore.

“We should be saving the property from vandalism, not challenging people to destroy it by putting boards over the windows and doors.”

Northdown House was left to the people of Margate and Cliftonville by the Friend family in 1937.

William Friend, whose grandfather was a previous owner of the Georgian manor house, insists that Thanet council has “no right” to sell the building.

Margate Labour Cllr Iris Johnston, who helped organise a petition calling for a halt to the council scheme, said: “If the building isn’t being used, it is effectively rendered worthless and therefore this is becoming something of a self-fulfilling prophecy.

“I fear that selling off Northdown House would have huge social implications for the people who use the building, particularly elderly residents.”

Thanet council is currently seeking legal advice to find out whether the propety can be sold.

Money raised from its asset management programme would be invested in new facilities, such as a new swimming pool in Ramsgate.