This Lady Elizabeth Percy's Wikipedia article is here.
From www.myspace.com/vladquigley 17th Century décolletage fashion.
The Countess wears a dress with what appear to ornamental buttons down the front of her bodice. Her sleeves are also not slashed.
Keywords: 1650, Lely, Elizabeth Percy, Countess, Percy family, Capell family, British, long straight coiffure, scoop neckline, chemise, modesty piece, three quarter length puffed sleeves, lining, buttons, full skirt, wrap