Her article in thepeerage is here. A portrait of her daughter is here.
From Wikimedia.
Lady Elizabeth wears a dress with inner short puffed sleeves under outer full sleeves, a fashion that would continue for another decade.
Keywords: 1821, Lawrence - Thomas, Elizabeth Conyngham, Denison family, Conyngham family, Countess, British, curly coiffure, off shoulder square neckline, modesty piece, dual upper puffed sleeves, cuffs, waist band, jeweled buckle, Empire low waistline, close skirt, floral bodice ornament, necklace, bracelets