Her article in thepeerage is here.
From Wikimedia; I removed small spots throughout the image with Photoshop.
Lady Frances's hair is teased over her forehead and the sweetheart neckline of her dress is fringed with a thin pair of lace trims.
Keywords: Chalon, Frances Stuart, Francess Ryder, Viscountess Sandon, Countess of Harrowby, Stuart family, Ryder family, Countess, British, curly coiffure, sweetheart neckline, bertha, lace, epaulettes, tight sleeves, belt, jeweled belt buckle, Empire waistline, floral bodice ornament, wrap