This portrait descended in the Byrd-Harrison family at Brandon plantation. The subject cannot be firmly identified. In the nineteenth century, he was called “Col. Allston of South Carolina.” The history of this identification is unclear and neither the Byrd nor the Harrison family have clear connections to the Allston family of South Carolina. Unless this is the unidentified “Mr. Brent” from the 1813 will of Mary Willing Byrd (Mrs. William Byrd III) of Westover, then it has no direct, documented connection to the Byrd family portrait collection. It may be a Harrison family member or an English acquaintance.
The portrait features a man wearing a Van Dyck costume in a style that was popular in the 1760s and 1770s. It is was likely painted in England.
See: W.S. Morton, “The Portraits at Lower Brandon, and Upper Brandon, Virginia,” William and Mary Quarterly 10, no. 4 (October 1930): 338-340.