March 4, 1759 - March 11, 1820
Thomson was tutored at Gunston Hall. In 1781 Thomson served in the militia. According to his father, his performance was marked by "proper Coolness & Intrepidity." However, by January 1783 he was managing the estate of his brother, George Mason V, while George was away in France. Also in 1783, his father assisted Thomson in setting up a snuff manufactory with William Allison, although this enterprise proved to be short lived. Thomson was married in 1784; he and his wife, Sarah, lived at Gunston Hall after their marriage. Their first two children were born at Gunston. In 1787 Thomson was building his own house, Hollin Hall, named after an estate of Thomson ancestors in Ripon, Yorkshire, England. He was given the Hollin Hall estate, situated on Little Hunting Creek, by his father.
In late 1788 Thomson and his family moved into a Hollin Hall still under construction. Work was still going on in 1792 for George Mason was interested in ordering "Cypress Scantlin, for the Columns, Rails, Balusters &c. of the piazzas and steps" and chimneypieces of Thomson's house. Throughout his life Thomson served in several public positions including Collector for the Port of Alexandria and justice of Fairfax County. New Englander Elijah Fletcher boarded with the Masons at Hollin Hall while he taught school in Alexandria in the early 19th century.
Sarah McCarty Chichester of Newington, 1784
Thomson Francis Mason, 1785 - December 21, 1838
Ann Eilbeck Mason, 1787 - 1845 (both of the above children were born at Gunston Hall)
Elizabeth Thomson Mason, 1789 - September 2, 1821
George William Mason, May 4, 1791 - June 11, 1855
Sarah Chichester Mason, ? - ?
Richard Chichester Mason, May 4, 1793 - July 22, 1869
Mary Thomson Mason, ? - April 18, 1837
John Mason, 1797-1821
1. Papers of George Mason, III: 1266-1267, 1271-1272.
2. Elijah Fletcher, Letters, edited by Martha von Briesen. Charlottesville: University of Virginia Press, 1965.