The identification of the sitter supplied by an old handwritten label inside the box is difficult to substantiate. Several other enamels by Zincke said to depict Sarah Jennings, Duchess of Marlborough (1660-1744) have recently been published but are as a group resemblance-wise incoherent. It may be excluded that the three Zinckes in the Gilbert Collection identified as Duchess of Marlborough depict the same sitter (S. Coffin/B. Hofstetter, The Gilbert Collection. Portrait Miniatures in Enamel, London, 2000, pp. 116-117, nos. 66-68). Comparison with the Zincke of 1711 in the Royal Collection is equally not conclusive ('Portrait Miniatures from the Collection of Her Majesty Queen Elizabeth II', Exhibition Catalogue, Metropolitan Museum of Art, New York, 1996/1997, et al., no. 46, pp. 138-139).