From Wikimedia.
Princess Mary's dress is much more elaborate than in the preceding print with a constructed bodice, bertha, and dual sleeves. The high waistline suggests this is still the 1810s.
Keywords: Princess Mary (1776 - 1857), Welf family, Princess, Duchess, British, straight coiffure, circlet, off shoulder neckline, bertha, dual upper puffed full sleeves, cuffs, waist band, Empire waistline, train, close skirt, necklace, fan