Selling country houses to new private owners is familiar to the National Trust, and one of America’s leading preservation trusts, the Colonial Williamsburg Foundation, has done just this. In the expansionist mood of the 1960s, the Foundation had bought Carter’s Grove, one of the finest plantation houses on Virginia’s James River. Just six miles from the colonial capital, it came with a mile of spectacular river front.

The intention was to show life on an 18th-century country estate, restored and rebuilt with Rockefeller money from the 1920s onwards. The Foundation made a huge investment in Carter’s Grove. Its English archaeologist, Ivor Noel Hume, carried out pioneering garden archaeology and re-created the formal gardens. Further finds of an early 17th-century English settlement as well as Native American artefacts were displayed in a new grass-roofed museum skilfully submerged in the landscape.

Recently, faced with harder times, the Foundation has decided to retract and concentrate on its numerous properties in Williamsburg. It has achieved what it calls a “protected sale” with easements (covenants) preventing development on the 400-acre estate. The purchaser is an internet wizard, Halsey Minor, whose company CNET delivers online information about technology. He has bought the estate for $15.3 million (£7.67 million) and intends to breed horses there.

One key question was what further controls could or should be imposed on the buildings and interiors. Carter’s Grove was built between 1750 and 1755 for Carter Burwell, grandson of Robert King Carter, the richest man in the English colonies. The panelling is considered to be some of the most handsome of the colonial period, the work of the English joiner Richard Bayliss.

In 1928 the estate was bought by Mr and Mrs Archibald McRea. Mrs McRea had originally been set on another James River plantation house at Westover and she raised the roof at Carter’s Grove to make it look more like the house she had failed to buy. She also stripped the paint on the panelling in the four main rooms to show the grain of the natural pine. The pine is not the familiar blond knotted pine used in England, but Virginia yellow pine, which has the colour of the finest oak panelling. As she used a leading Colonial Revival architect, W Duncan Lee, these alterations have an interest in themselves, and Williamsburg fought hard to protect them. Now control will be exercised by Virginia’s Department of Historic Resources.

Another issue concerns the slave quarters, re-created from archaeological evidence with simple cabins and a black overseer’s cottage. They were painstakingly built using 18th-century tools and techniques with nails made in the Williamsburg smithy. Furnished with straw mattresses, gourds and ceramic vessels, they were the scene of evocative evening re-enactments of slave life. At present the Foundation intends simply to “memorialise” them with a plaque.

Ivor Noel Hume, potentially the fiercest critic of the changes, says: “I have met Mr Minor and am very impressed. He plans to carry out further archaeology and research and has the best intentions for the house.”