This is the Tate Collection's caption for this image, "Sir John Anstruther commissioned this portrait of his wife, Janet, along with his own portrait (now in a French private collection). Lady Anstruther, the daughter of a Scottish merchant, was renowned for her beauty and for her reputation as a flirt. Despite her social elevation through marriage to a baronet, on at least one occasion Lady Anstruther was taunted in the streets for her supposed gypsy descent. In Reynolds's portrait, she glides serenely through the grounds of a landed estate, her dress and deportment asserting her right to be recognized among the ranks of the aristocracy."
Upgrade image posted on 4 May 2013 from the Tate Web site.