In spite of all of the genealogical information in the caption, I could not locate an entry for her in thepeerage. However, there is a Wikipedia article for 2nd Baronet Edward Littleton who married twice and named a daughter from each marriage Mary. This is probably a portrait of the first Mary whose mother was Mary Wrottesley; her parents and siblings are mentioned in thepeerage, but not her. There is a Wikipedia article about the Gough-Calthorpe family that mentions a Henry Gough, but has nothing about his family.
From oldrags.tumblr.com/page/3.
Lady Mary Gough wears a relatively untangled hurluberlu coiffure and a typical dress with puffed slashed sleeves in this Beale portrait from about 1670.
Keywords: 1670, Beale, Mary Gough, Mary Littleton, Littleton family, Gough family, chemise, modesty piece, off shoulder scoop neckline, bodice, puffed over-sleeves, slashed sleeves, necklace, earrings, heweled bodice ornament, clasps, wrap