Sarah, Lady Cowper (1701-58). Not to be confused with her better known grandmother, the diarist of the same name the Sarah Cowper pictured here is the daughter of William First Earl of Cowper. The portrait is taken from an enamel picture by Lincke that was owned by the Rt. Hon. Lady Llanover, Mary Delany's great-great niece and the editor of the published volumes of The Autobiography and Correspondence of Mary Granville, Mrs Delany: with Interesting Reminiscences of King George the Third and Queen Charlotte (3 vols, London: Richard Bentley, 1861-2). This print is possibly a plate from those volumes.  Lady Cowper  was an acquaintance and correspondent of Mary Delany and was  said to be 'distinguished for her sense and accomplishments'. She died unmarried in 1758.