The Grade I-listed house had been abandoned for more than 50 years and was in a precarious state, with snow blowing into the library and trees growing through the walls, when the 12th Earl of Shaftesbury inherited the property in 2005, aged just 25.
With the help of grants from Natural England and the Country Houses Foundation, the Earl and Countess of Shaftesbury embarked on a 4.5 year restoration project. As well as extensive works on the house itself, parkland buildings within the 5000-acre estate and a two-room grotto with walls lined with shells, fossils, coral and stone were also restored.
Other commended properties from the awards shortlist included the Palladian Bridge, a previously lost feature of the Grade I-listed 18th century park at Hagley Hall in the West Midlands.
The award seeks to generate publicity for the winning properties and encourage more visitors.