Sandiway House in Hartford, Cheshire has been sold by engineering giant Amec to a private investor who intends to return it to residential use.
The buyer will have to undertake a substantial refurbishment of the property to remove raised floors and other office specification and create new room layouts before he can move in.
The original 9,000 sq ft mansion house dates back to 1860. A 15,000 sq ft office extension was added in the 1980s. There are also 3,000 sq ft of outbuildings and five acres of grounds.
Amec vacated the premises around 18 months ago and moved to Bruntwood's new building at the rear of Booths Park in Knutsford.
The sale, which was secured for an undisclosed sum by CB Richard Ellis on behalf of Amec, follows a successful planning application for the change of use into a single residential dwelling.
Before becoming the head office for Amec, Sandiway House was home to the Lord Lieutenant of Cheshire and his daughter, Katherine Worsley, now the Duchess of Kent.
Will Kennon, senior surveyor at CBRE, said "This was a challenging sale to advise on not only because of the current economic situation but also due to the lack of interest from office users and the scope of the building. The size of the site meant that we could consider alternative uses but we were keen to minimise Amec's exposure to risk. As a result, this sale was concluded on an unconditional basis subject to contract."