A print of Ann Donnellan. She has been described as a 'proto blue-stocking' and a friend  of Mary Delany, Elizabeth Montague and Jonathan Swift. She was a talented singer and musician and well-acquainted enough with Handel to be left a £50 legacy in his will. In this portrait she wears a lace mantle tied with a bow. 
 
The print was made by Joseph Brown after an enamel by Rupert Barber which was owned by the Right Hon. Lady Llanover.  Lady Llanover was 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.
 
Further Reading. 
Patrick Kelly, Ann Donnellan: Irish Proto Blue-stocking, Hermathena No. 154 (Summer 1993), pp. 39-68 (30 pages)  Trinity College Dublin