Her article in thepeerage is here.
From bbc.co.
Countess Margaret's chemise conforms precisely to the neckline of her dress and also appears to be combined with her sleeves to make cuffs.
Keywords: 1816, Owen, straight coiffure, chemise, sweetheart neckline, quarter length under-sleeves, cuffs, bodice, waist band, Empire low waistline, close skirt, brooch, bracelets, wrap