According to her article in thepeerage, Jean became Duchess of Gordon upon her marriage. This portrait may commemorate her marriage accession to the title. Scatologically, her article in thepeerage states, “...She died on 27 July 1824, without legitimate issue.” Meow!
From artuk.org; fixed upper edge with Photoshop.
Duchess Jean is placed here based on what appears to be an A-line skirt. Her dress includes a partlet, complete with neckline ruff (or is that her chemise).
Keywords: Raeburn, Jean Christie, Jane Christie, Jean Gordon, Duchess of Gordon, Duchess, British, Christie family, Gordon family, Duchess, British, curly coiffure, frill-edged cap, rosette, strap, chemise, high enclosing neckline, neckline ruff, bodice, long close sleeves, Empire waistline, A-line skirt, wrap