William St Clair of Roslin

William Saint Clair of Roslin, 21st Baron of Roslin (died 1778) was a member of the Clan Sinclair. His title, Baron of Roslin was not a peerage but a Scottish feudal barony. He had an interest in sport and was a skilled golfer and archer. He was a freemason, being initiated to the fraternity on May 18, 1736. He is also known as the first Grand Master of the Grand Lodge of Scotland. He was elected to the office on St. Andrew's Day of the same year (1736).

Source

http://freemasonry.bcy.ca/biography/stclair_w/stclair_w.html