The Clan Sinclair Trust is a Scottish trust which was formed with the main objective of rescuing and preserving Castle Sinclair Girnigoe and of developing a visitor centre and library. Over the years, the Trust has raised substantial funds which have been spent on the castle including major works to stabilise the remaining building and on conducting major archaeological research which has resulted in highly important historical discoveries.
The patron is the His Royal Highness Prince Charles, Duke of Rothesay. Chief Executive is Malcolm Sinclair, 20th Earl of Caithness and John Sinclair, 3rd Viscount Thurso and Euan Sinclair are trustees.
The Trust's 2006 Financial Statement reported that in April of that year "the Trust acquired Noss Head Estates Limited, a privately owned company" with a generous donation from Niven Sinclair and his cousin Sandi Sinclair Pershing from the US. The purchase was from Ian Sinclair and Joan Burton and comprised 35 acres of land at Noss Head, together with two houses and outbuildings. Ian Sinclair was to continue to live in the house on the land in life-rent with his partner Joan Burton and a lighthouse situated there remained the property of the Northern Lighthouse Board.
The Trust advised in 2009 that it hopes to establish a clan centre when funds permit.