The Sinclair (later Sinclair-Lockhart) Baronetcy of Stevenson in the County of Haddington, is a title in the Baronetage of Nova Scotia. It was created on 18 June 1636 for John Sinclair of Stevenson, with remainder to his heirs male whatsoever. The third Baronet was a Baron of the Exchequer and member of the Privy Council of Scotland. The fourth Baronet married Martha, daughter and eventual heiress of Sir John Lockhart of Castlehill, a Lord of Session under the judicial title of Lord Castlehill. The eighth Baronet was an Admiral in the Royal Navy. On the death in 1899 of his son, the ninth Baronet, the title passed to a descendant of James Sinclair, younger son of the fifth Baronet, who in 1764 had inherited the Lockhart estates and assumed the surname of Lockhart. The tenth Baronet was a m