This could be Frances, Sophia, or Sarah Delaval.
From the Tate Web site.
Revolution? What revolution? Coiffures and dresses continue in the UK from the 1780s.
Keywords: 1792, Delaval family, bouffant coiffure, ribboned hat, scarf, bows, fichu, scoop neckline, long close sleeves, waist band, double vee waistline