From www.the-athenaeum.org; image made lighter to bring out details by gogm.
Lady Louisa's cap with an abundance of pleats is noteworthy.
Keywords: 1775, Romney, Louisa Conolly, Louisa Lennox, Lennox family, Conolly family, British, high straight coiffure, cap, pleats, choker neck band, criss-cross bodice, high neckline, coat, collar, lapels, lining