Her article in thepeerage is here. She married twice, first to Robert Lucy and then to Thomas Arundell, and had a child by each marriage.
From artuk.org.
The capelet adds an unusual note to Lady Margaret’s dress as do her seemingly wide open sleeves puffed with nothing more than air.
Keywords: 1652, Margaret Spencer, Mrs. Robert Lucy, Baroness Arundell of Wardour, Spencer family, Lucy family, Arundell family, Baroness, British, proto-hurluberlu coiffure, chignon, hair jewelry, earrings, necklace, modesty piece, vee neckline, capelet, off shoulder vee neckline, brooch, basque bodice, three quarter length puffed sleeves, turned back cuffs, spoon waistline, close skirt