One of Europe's biggest private stately homes is due to be sold to a Hong Kong based investment company.
The Grade I listed Wentworth Woodhouse, near Rotherham, South Yorkshire, is larger than Buckingham Palace. It was on the market since May with a price tag in excess of £8m.
Estate Agents Savills said it had agreed a sale with Lake House Group but would not disclose the selling price.
Lake House Group said it was "delighted to be involved with the purchase".
"It is our hope that we can work with some of the organisations which have also shown an interest in the property in order to save and preserve this magnificent historic house", the company added.
Savills said the buyer was due to exchange contracts and complete the purchase "shortly".
An estimated £42m is needed to spend on repairs, campaign group Save Britain's Heritage says.
The Georgian mansion, which is open to the public, sits in 82 acres of grounds and the earliest wing of the house was started in 1725.
The Palladian-style east wing has a front that extends for 606ft (184m).
It was bought in 1999 by architect Clifford Newbold, who died in April. His family made the "reluctant decision" to sell the property after his death.
Restoration work was under way but it had been hampered by subsidence caused by mining, which was a key source of income to help with running costs for the house's former owners.
The interiors of the house are the work of three patrons - the First and Second Marquess of Rockingham and the Fourth Earl Fitzwilliam.
The history of Wentworth Woodhouse and the nearby village of Wentworth is linked with three aristocratic families, the Wentworths, Watsons and Fitzwilliams.