The Sherborne branch of the Campaign to Protect Rural England (CPRE) has said it is “deeply concerned at the parlous state” of Newell House, a Grade II listed building at the junction of the A30 and Marston Road.
The CPRE says the western side of the house is thought to date back to the 17th century and the house was listed as far back as 1950 but has now deteriorated and is on the At Risk register.
Alongside the house is a listed barn that dates back to the early to mid-16th century.
Sherborne CPRE chairman Sir Christopher Coville said: “Despite approaches to Dorset Council at the highest levels, it is clear that our county representatives are either powerless or disinclined to take any positive action to preserve our precious heritage buildings.
“We find it disappointing that a house listed 72 years ago by an official government agency is then effectively abandoned by local authorities when it deteriorates. It is sadly ironic that as Sherborne House is being transformed into a remarkable asset for the town centre, another even older much-loved building has been allowed to become derelict.
“Something must be done before it is too late.”