About John Sinclair, of Stevenson, 4th Bart.
"Sir John Sinclair, Baronet [S 1636] of Stevenson, son and heir by 1st wife; M.P. [S] for Lanarkshire, 1702-07, and an opposer of the Scotch Union; succeeded to the Baronetcy, July 1713; was a staunch supporter of the Hanoverian Succession. He married in 1698, Martha, widow of Cromwell Lockhart, of Lee, co Lanark, daughter and eventually sole heir (on the death of her brother) of Sir John Lockhart, of Castlehill, in that county, a Lord of Session [S], under the title of Lord Castlehill. He died 1726. His widow, died at Stevenson, 15 May 1752."
SOURCE: Complete baronetage; Cokayne, George E. (George Edward); 1900; Vol. II; page 422