Of Agnew in the parish of Kirkcowan, Galloway. Son of Patrick Vans of Barquhanny and Barnbarroch (ca. 1694-1733) and Barbara McDowall, daughter of Patrick McDowall of Freugh. Married (1747) to Margaret Agnew, dau of Robert Agnew of Sheuchan, and Margaret McDowall. John Vans and his wife were thus first cousins, their mothers being sisters.
In 1771 Vans had built the family's present seat of Barnbarroch. He had at least six children. His eldest son, Robert Vans Agnew (1755-1809), succeeded him as Laird of Barnbarroch and Sheuchan.
According to a family history, John Vans was
a gentleman of much ability and integrity, who led a country life, and was remarkable for the influence which he acquired by the superiority of his talents and the urbanity of his manners, and whose memory was long cherished in Wigton and neighbouring counties, not only for his philanthropy, but for the unwearied attention which he paid to the agriculture and general improvement of the country.1
- 1Quoted from William Balbirnie's "An Account of the Family of Vance in Ireland, Vans in Scotland, and originally de Vaux in France" (1860), p. 22
Boswell met John Agnew at Kirroughtrie (the Heron estate) on September 29, 1762. He described him as "a genteel, ingenious gentleman".