Her article in thepeerage is here.
From oldgreypony.wordpress.com/tag/georgian-portraiture/.
Elizabeth Courtenay wears a British casual dress and a lightweight coat or jacket for this Cosway miniature from about 1788. Both her dress and coat could have a ruff.
Keywords: 1788, Cosway, Elizabeth Courtenay, Courtenay family, Somerset family, British, bouffant coiffure, hair jewelry, vee neckline, collar, ruff, close sleeves, waist band, bows, natural waistline, coat, quarter length close sleeves, necklace