A 402-year-old Grade-I listed building which has been used as a police training college for decades is to be sold and turned into a residential site.
The Home Office will sell its Bramshill House, which also includes a Grade-II listed park of medieval origins, to heritage property developers City and Country.
The Jacobean building was bought by the Government department in 1952 and developed into a national police training college.
The sale price will become public knowledge when the deal is completed and recorded at the Land Registry - but it was previously reported the property was up for more than £20 million.
A Home Office spokesman said: " We can confirm we have agreed to sell the Bramshill site to City and Country, part of the City and Country Group.
"Although Bramshill has a proud history of police leadership training, it is not sustainable. Its closure will save £5 million a year and is another example of how this government is delivering greater value for money for the taxpayer.
"City and Country has a proven track record for the successful restoration and conversion of listed properties of great historic interest to new uses and to a high standard.
"The company has committed to finding new uses for this historic building which would allow partial public access to the site to continue."
The Hampshire site is currently occupied by the College Of Policing, which will relocate by the end of March 2015. Bramshill is also home to the European Police College (Cepol), which all EU member states have agreed will relocate to Budapest to continue its work.
Contracts have been exchanged with City and Country, which intends to develop the site for residential use.
In 2011 the National Policing Improvement Agency (NPIA) was criticised for spending more than £18,000 of taxpayers' money on the mansion and its grounds, including £1,800 on a beehive and cultivator for the kitchen garden, and £147 on rhododendrons.
And in the previous year, the agency was reported to have spent £750,000 on restoring an ornamental bridge.
The NPIA also spent £2 million resurfacing a mile-long stretch of the drive and spent £31,000 on a black tie dinner for officers at Bramshill in September 2007.
A spokesman for City and Country said: " We are delighted to announce the acquisition of Bramshill, which is a truly magnificent building with a distinguished history and of immense aesthetic and social value.
"We believe that our expertise and strong track record in dealing with very precious nationally important heritage assets combined with our sympathetic understanding of the sensitive legacy issues associated with this disposal, were some of the deciding factors in being successful in making this acquisition.
"We relish the challenge of working with key stakeholders and the local community to find a viable, new and beneficial use for this wonderful estate for the benefit of current and future generations."