A heritage study, which recommended Hotham House at Kirrawee be preserved, has been challenged by a new report commissioned by the site's owner.
Macquarie Health Group, which wants to demolish the house as part of redevelopment of President Private Hospital, engaged GBA Heritage to peer review the report prepared by Architectural Projects for Sutherland Shire Council.
GBA said there was a lack of evidence to support many of the claims, and the property did not qualify for heritage listing.
The GBA report said the stated connection between the house and the early 20th century poultry farming sector was "the mainstay" in the reasons advanced for preserving the house.
"Unfortunately, this recommendation is flawed...", the GBA report said.
GBA said the poultry farming operation, including growing feed, occupied a very large land area on both sides of Hotham Road, stretching to the north beyond the nearby railway corridor and to the west at least as far as Bidurgal Lane.
"The current house is located on a very small portion of land towards the south western corner of those extensive property holdings.
"All of the land actually used for the poultry farm was subdivided off and sold for residential development in the early post WW2 decades.
"The remnant land parcel is confined to that which immediately surrounds the house.
"The land between the house and President Avenue, which included a tennis court and home garden, was also sold and is now occupied by the President Private Hospital complex.
"The large Cook Pine tree in the centre of the circular garden path in front of the house does not appear in the 1943 aerial photo."
GBA said the terminology "homestead" was incorrect and suggested a rural property.
"The house was erected on a parcel of land within the late 19th century urban subdivision of the Holt-Sutherland Estate," the GBA report said.
"Despite being owned by three separate people between 1915 and the 1972, the actual house was not the site of significant advances being made in poultry breeding and raising.
"Such activities would have been located on the adjoining land, which has since been sold."
GBA disputed the claim Hotham House was an important social centre for local people in an isolated area.
An earlier study had revealed "a huge social gap" between the Tildersley family, which started the poultry farm, and local residents.
The GBA report said the fact the ballroom later accommodated parish dances and balls "was not sufficient to pass a threshold test for significant historical activity".
The council decided at its meeting in April to apply for a permanent heritage order, but a rescission motion is due to be debated at the May 20 meeting.