The portrait was sold by Matthiesen that has this note about the sitter in their notes for the portrait, "Countess Thérèse von Orsini und Rosenberg (1798-1896) married Count Eugène Czernin von und zu Chudenitz in Vienna on 27th May 1817. She was the daughter of Franz, Prince Orsini und Rosenberg." Their notes also include this, "We are indebted to Dr. Kenneth Garlick for confirming the attribution of this drawing to Lawrence. It would have almost certainly been executed during the artist's sojourn in Vienna between December 1818 and May 1819, although it does not appear on the list of his sitters which he sent to Joseph Farington from Rome..."
From From www.matthiesengallery.com.