This previously unrecorded portrait appears to depict Françoise-Athénaïs de Rochechouart de Mortemart, marquise de Montespan, known as Madame de Montespan (1641-1707) who was one of King Louis XIV's mistresses from circa 1667 to the early 1680s. She was of noble descent and married the marquis de Montespan in 1663, but this marriage which lasted until her husband's death in 1701 did not impede her from assuming the role of mistress to the Sun King.
The sitter in this portrait bears a close resemblence to other known portraits of Madame de Montespan, including another by Joseph Werner. The Werner portrait, now in the collection of the Duke of Buccleuch, depicts the marquise in front of a red marble balustrade as does the present composition. The physiognomy is quite close, and Madame de Montespan is known to have changed her hair color to blonde. The Duke of Buccleuch's ancestor, the 1st Duke of Montagu was a diplomat at the court of King Louis XIV from 1667-78, a period which coincides with Madame de Montespan's time as the King's mistress. Another portrait by Nicolas Mignard (fig. 1) at Versailles depicts Madame de Montespan with her three children in a setting similar to that of the two miniature portraits (inv. 38; C. Constans, Musée national du château de Versailles: Les Peintures, Paris, 1995, II, p. 646, ill.). The arched portico is depicted in both the Mignard and Buccleuch Werner portraits, as is the marble balustrades with a view of a garden beyond. The similarities in the settings suggest an actual place, perhaps the Château of Clagny, Montespan's residence next to Versailles which was a gift from the King.
Joseph Werner is recorded at the court of Versailles from 1762 to 1767. He is known to have executed six bodycolors to decorate the cabinets in the galerie d'Apollon in the Louvre, of which three are extant.
An attribution to Thomas Lefebure has also been suggested.