I cannot find any information about her.
From eBay. This is one of several prints of beauties in Queen Victoria's court released in 1849. The original was prepared a decade or so earlier based on her dress and coiffure.
Lady Seymour wears an Early Victorian side curl coiffure with a deep vee off shoulder décolletage.
Keywords: Seymour family, British, side curl coiffure, bun, vee décolletage, full skirt, brooch, clasps, wrap, lace