Clive Lucas, the NSW president of the trust, made the appeal directly to Premier Mike Baird this month in a letter arguing the government's assurances about the protections in place for the state heritage listed properties had been "proven wrong" by the damage done to one of Sydney's oldest homes.

In December, the Land and Environment Court NSW ordered Lloyd Adams to pay a $60,000 fine, as well as the City of Sydney's $35,000 court costs, after he caused irreversible damage to a colonial Georgian terrace house within a week of finalising the purchase of the 30 Argyle Place property for $1.71 million in 2014.

Mr Adams had removed internal plaster, skirting boards and other material of "exceptional" significance - and continued to do so even after the council's heritage officer directed him to stop.

Prior to the damage done by Mr Adams, the address had been identified as the "most intact" of the small row of terrace houses, of which the court's judgment noted "no other surviving mid 1840s examples have been located".

Even if repairs were undertaken, "they would not restore the interiors of the house or wholly compensate for the diminution in heritage significance caused by the loss of the original fabric and elements of the interiors," Brian Preston, chief judge of NSW Land and Environment Court, found.

The judgment said a "remorseful" Mr Adams, who later complied with a formal stop work order, "seems not to have read ... in any detail" a conservation management plan he was required to sign along with the contract of purchase.

*/ ]]>

In his letter to Mr Baird, Dr Lucas said the trust had questioned back in 2014 how 293 state heritage listed terraces could be sold freehold "over a short space of time" to individuals with the resources "to properly conserve these heritage icons".

"I must express the deep disappointment and concern of the Trust and its members at the State Government's failure to adequately protect these unique properties," Dr Lucas wrote.

"The Trust again calls on the Government to only sell the remaining properties in Millers Point/Dawes Point/The Rocks by 99-year lease with appropriate bonds in place."

Such a change "will not reduce the return more than 5-10 per cent, and ensure that their heritage values remain protected," Dr Lucas added.

However, the government has since announced that it would instead speed up the sell-off of the area's public housing, with more than 50 more properties to be listed for sale this financial year.

These sales are expected to reap a windfall of $100 million, in addition to the $116 million from 47 properties sold since August 2014.The state government has said the proceeds would be reinvested in social housing.

A Government Property spokesman said all purchasers were "fully informed" about their responsibilities through the conservation management plans and any breaches "may be enforced by law".

"Conservation Management Plans are applied to both leasehold and freehold properties so the protections are the same," the spokesman said.