thoroughly rebuilt, in about 1730–33 (the latter date is on rainwater heads) by Thomas Onslow, 2nd Baron Onslow to the design of the Venetian architect Giacomo Leoni. It is a rectangular building of red brick and stone dressings. Clandon House interiors, completed in the 1740s, featured a two-storey Marble Hall, containing marble chimney pieces by the Flemish sculptor Michael Rysbrack, and a rococo plasterwork ceiling by Italian-Swiss artists Giuseppe Artari and Bagutti. Clandon Park was landscaped by Lancelot 'Capability' Brown in 1776–81, replacing a French garden and transforming part of a disused canal into an ornamental lake. A porte-cochère was added to the principal facade in 1876. A sunken Dutch garden was created by Frances, Countess of Onslow at the north front of the house in the late 19th century. In 1895, the house was investigated for paranormal activity by the Marquess of Bute and Ada Goodrich Freer on behalf of the Society for Psychical Research. During World War I, the Onslow family created and managed a hospital in Clandon House for the war injured. Slavery The house was built with the profits from slavery. Elizabeth Knight inherited her wealth from Charles Knight, her uncle. Charles was a slave trader and plantation owner. Elizabeth inherited a plantation called Whitehall in St Thomas-in-the-East, Jamaica, and the enslaved workers who worked there, producing sugar and rum. Elizabeth's husband Thomas Onslow was the founder of a ship insurance company that dealt with slave ships. The slave plantation was passed down the generations of the Onslow family. At any one time between 87 and 150 enslaved people were captive on the plantation. Acquisition by the National Trust In 1945, ownership of Clandon House was passed in trust to William Onslow, 6th Earl of Onslow on the death of his father, who had offered Clandon House to be used by the Public Record Office to protect government documents from destruction by bombs in the war. The family moved out to facilitate this. In 1956, the Earl decided that he wished to donate Clandon House to the nation. The house could not be donated directly by the Onslows, so the Earl arranged for his aunt, Gwendolen, Countess Iveagh, the daughter of William Hillier, 4th Earl of Onslow and a former MP herself, to purchase Clandon House from the Onslows for £1. The National Trust would only accept the house if it also received a substantial monetary