Nicholas Dixon, About 1645-after 1708
Portrait of an Unknown Woman
About 1675
Watercolour on vellum, stuck to a table-book leaf
Signed lower left 'ND' in monogram
Museum No p4-1942
Given by the National Art Collections Fund

This is possibly of Frances Theresa Stuart (1657-1701). But Dixon's miniatures of court beauties were so idealised it is difficult to be certain. Frances Theresa was rumoured to have been one of Charles II's mistresses.