Susannah-Penelope Rosse was the daughter of the miniature painter, Richard Gibson, and his wife Anne. She too became a miniature painter, and George Vertue records that 'her first manner she learnt of her father, but being inamour'd with Cooper's limnings, she studied & copy'd them to perfection'. Her family was intimately connected with Samuel Cooper's as the parents of her husband, jeweller Michael Rosse, occupied Cooper's home in Henrietta Street, Covent Garden, after Cooper's death. Many finished and unfinished miniatures by Samuel Cooper came into the possession of Michael Rosse, perhaps directly from the artist's widow, and were sold in the sale of his collection in April 1723. The present miniature has been heavily retouched, but has been attributed to Susannah-Penelope Rosse on the basis of comparison with a series of unfinished miniatures by her which remain in the Victoria and Albert Museum, London and which show an awareness of Samuel Cooper's studio routine (see for example, Mrs Priestman, P452-1892). The miniature is inscribed on the reverse with the identification Sarah Duchess of Marlborough and does indeed bear some resemblance to the bust-length portrait of the Duchess of Marlborough by Sir Godfrey Kneller of c. 1690-5. Sarah, daughter of Richard Jennings, married in 1678 John Churchill, who was created first Duke of Marlborough in 1702. For many years, she enjoyed influence at court as favourite of Queen Anne.