On vellum, in a gold frame, 8.4cm.
The lady is depicted with centre-parted and side curled hair, wearing a low-cut gold embroidered grey dress with a white chemise and blue drape.
Louise de Kéroualle was born into a noble Bretonne family. She came to England in 1670 in the retinue of Henriette Anne, Duchess of Orléans, a sister of Charles II, and shortly afterwards she became his mistress.
She was created Duchess of Portsmouth by the king in 1673, shortly after the birth of their son Charles, who was created Duke of Richmond in 1675.
Peter Cross was perhaps a pupil of the great miniaturist Samuel Cooper (1609-1672), whose work he closely imitated. He enjoyed great popularity as a limner during the reign of Queen Anne (1702-1714) and there are many of his miniatures in the Royal Collection.
He also formed his own important collection of miniatures by many of the great limners of the day.