Finding an article about her in thepeerage took some doing. The Frasers of Castle Fraser were, according to the Wikipedia article about Castle Fraser known as Mackenzie-Fraser. Thepeerage has an article for a Charles Mackenzie-Fraser, 1792-1871, that links to an article for Jane Hay who married him in 1817.
Lawrence again shows off a sweetheart neckline in this portrait of Jane Hay, named Mrs. Charles Fraser of Castle Fraser, from about 1817. She may be wearing a coat pulled well back, but it is more likely she is wearing a Spencer of red-maroon velvet.
Keywords: 1817, Lawrence, Jane Hay, Mrs. Charles Mackenzie-Fraser, Mrs. Charles Fraser of Fraser Castle, Hay family, Mackenzie-Fraser family, British, curly coiffure, bun, modesty piece, trapezoidal neckline, criss-cross bodice, vee décolletage, waist band, Empire low waistline, close skirt, jacket, Spencer, fur, lining