The house was built in around 1730 in the Palladian style by the Venetian architect Giacomo Leoni for the 2nd Baron Onslow. It was constructed of red brick, with the west front faced in stone.
In 1876 a porch was added to the front door but no other changes have been made to the house.
The interior has also survived virtually intact.
The magnificent original plaster work, for which Clandon is famous, decorates the splendid two-storey Marble Hall and other rooms. In the latter part of the 18th century some changes were made to the decoration in the Adam style, with cut-glass chandliers, gilt mirrors and flock wallpaper.
Clandon Park was given to the National Trust in 1956 by the Countess of Iveagh, daughter of the 4th Earl of Onslow.
However, the house was empty when the Trust acquired it and the contents displayed today are from the bequest by Mrs David Gubbay of Little Trent Park in Hertfordshire.
These include a superb collection of porcelain, furniture and needlework. The old kitchen has an array of cooking utensils and the original range.
The house provides a facinating view of the contrasting lifestyles of the ruling and serving classes of the 18th century. In the basement is the museum of the Queen's Royal Surrey Regiment.
The gardens extend to seven acres and include a Maori House brought from New Zealand in 1892.