He was the great-grandson of William Thornton, who had arrived in Virginia from England as late as 1646, settling in Gloucester County.
Presley was also a distant cousin of the future presidents, James Madison and Zachary Taylor.
He was elected to represent Northumberland in the House of Burgesses in 1748–1749 and returned in 1752–1761 and was appointed to the King's Council in 1760.
The younger Thornton was pardoned and restored to full citizenship in 1783 and retained ownership of Northumberland House until 1800, at which time he sold the entire estate and moved to Genesee Country in New York, where he died in November 1806 in Bath, Steuben County, New York.
His second wife was Charlotte Belson, the adopted daughter or ward of Colonel John Tayloe of Mt.