Three family names. How can that be? According to her article in thepeerage, she was born Maria Theresa Villiers, married Thomas Henry Lister in 1830, and then married Rt. Hon. Sir George Cornewall Lewis in 1844. She bore a daughter by Thomas Henry Lister. Google searching disclosed that she was an author.
From www.gutenberg.org/files/41400/41400-h/41400-h.
Mrs. Lister is probably portrayed at about the time of her marriage to to Mr. Lister in 1830 based on the sleeves. Her high-peaked pointy hat is used to mount a lace veil, akin to a mantilla. This is probably folk costume, possibly from Valencia.
Keywords: Newton, Maria Theresa Villiers, Mrs. Lewis, Mrs. Lister, hat, veil, lace, trapezoidal neckline, wrap, square neckline, quarter length puffed sleeves, bows, full skirt, necklace, earrings, bracelets, theatrical dress