A biographical article about her is here.
From bbc.co; spots removed from background woth Photoshop and shadows filled in.
Lady Margaret wears a very simple dress with the wide lace collar typical of the 1630s and a coiffure patted down over the top of her head in this 1634 Jamestone portrait.
Keywords: 1634, Jamestone, Margaret Douglas, Marchioness of Argull, Douglas family, Campbell family, Marquise, British, straight coiffure, ribbon headdress, rosette, trapezoidal décolletage, modesty piece, bertha, lace, puffed sleeves, waist band, shallow vee waistline, necklace