From eBay. This is one of several prints of beauties in Queen Victoria's court released in 1849. The original was prepared over a decade earlier based on her dress.
Lady Margaret wears a middle 1830s dress with a wide waist band, imbecile sleeves, and full skirt beneath an Apollo knot.
Keywords: Mary Egerton, Stanley family, Egerton family, Countess, British, straight coiffure, Apollo knot, feronniere, off shoulder vee neckline, modesty piece, lace, imbecile sleeves, bows, cuffs, waist band, full skirt