According to marriage records in the Maryland Historical Society, Gladston Colston married Mary "Polly" Voss in Dorchester County, MD 1 Nov 1791.
According to my research, I believe the following is her line of descent:
James Vaulx (called "medicus" because he was a doctor) of Marston Meysey, Wiltshire, England died 30 Jan 1631/32. By his wife Elizabeth Gynnor (als Jenner) he had son Robert bap. 22 Oct 1615 who came to Virginia about 1642. His brothers Thomas and Humphrey Vaulx also came to Virginia.
I am unsure about Robert's wives as I believe he had more than one. It seems one of them was Elizabeth Burwell.
In any case, it seems Robert had a son James Vaulx born in Virginia about 1638. He married Elisheba last name unknown. James died about 1678 in Virginia and his wife remarried to a John Frank either in Virginia or in Northampton County, Virginia where she resided until her death. Her husband John Frank died intestate in 1713. Elisheba (Vaulx) Frank died intestate in 1719.
James and Elisheba Vaulx had a son Robert Vaulx who was probably born about 1662. He married Elizabeth last name unknown. Their son was Francis Vaulx/Voss/Vass who died before July 1745. His wife was Mary Eccleston of Dorchester County, Maryland who was the daughter of Hugh Eccleston of Dorchester whose will was proved 2 Apr 1713.
Francis and Mary Voss had a son Robert Voss whose wife may have been Ann "Nancy" Thomas. Their daughter was Mary "Polly" Voss who married Gladston Colston. I have it from another researcher that Mary "Polly" was born 24 Aug 1763. I understand there is an old Bible record located in Ross County, OH that gives her parents as Robert and "Nancy."
Gladston Colston must have died some time before 15 Nov 1804 because on that date, his widow Mary "Polly" remarried in Dorchester County to Edmond Brannock. I have searched the probate records of Maryland but can find no administration of the estate of Colston. I believe some of the Dorchester records are missing, so his probate files may be among those missing.
One source says she married again to a George Ater and died in Ross County OH in 1857 where she is burried in Clarksburg, Ohio behind the Methodist Church there. Supposedly, on the stone is says Mary Ater wife of George Ater. Her will is in Ross County.
James Vaulx "Medicus" descends from the armorial family Vaulx of Catterlyn. The first of this line in England was Harold who came with the Normans. He settled in Cumberland, England, near Penrith, in the parish of Newton-Reigny. Harold had several sons including Robert, Hubert, and Ranulf. Hubert was Lord of Gillesland; Ranulf Lord of Tryermain, and Robert Lord of Catterlyn. There are records of this family going even further back into France where they Vaulx family was of record as early as the 8th century. The Castle of Vaux or de Vallibus (a Latin version) is mentioned by the historian Ordericus Vitalis as being in existence in the year 775. Several of the descendants of Harold were among the Magna Carta barons. There are published pedigrees of this Vaulx family that show the descent from Harold. One member, probably John, moved to Wiltshire, England. You can find the 1623 Visitation of Wiltshire here: http://www.uk-genealogy.org.uk/england/Wiltshire/visitations/index.htmlhttp://www.uk-genealogy.org.uk/england/Wiltshire/visitations/index.html. It contains the pedigree of James "Medicus" and shows his son Robert.