The identity of the sitter is uncertain, but she may be Margaret, the widow of the Hon. Francis Coventry, who, in 1701 married Sir John Thorold, 4th Baronet and Member of Parliament for Grantham and Lincoln. Sir John died in 1717, Lady Thorold in 1733. The miniature, although dated 1721, may have been copied from a painting of a slightly earlier date, but the original is not known.

The artist, Christian Richter (1678-1732), was born in Stockholm and settled in London in 1702 where his compatriots, Hans Hysing and Michael Dahl, had thriving British practices. Many of Richter's miniatures are copies from full-scale portraits by leading artists. Richter began his career as a silversmith then moved to miniature painting, first on vellum and later on enamel. George Vertue, the engraver and antiquary, described Richter's style: 'his Manner of Painting very tender and Curious, his tincts had a great variety his pencil regular and neat, his lines of drawing very just & toucht with freedom'.

Signed and dated on the back in pencil: C Richter [initials in monogram] 1721 Ledy Thorold, though it could be read as Horrold.