From the Christie's Web site; size fixed at 40 cm at 29.35 pixels/cm.
This can be regarded as a close up from the last image, at least as far as the mammoth coiffure is concerned. She may be wearing a zone bodice or a wrap with ends ties with a knot at her neckline.
Keywords: Gainsborough, Anne Thistlethwayte, Countess of Chesterfield, Thistlethwayte family, Stanhope family, Countess, Countess of Chesterfield, British, high straight coiffure, modesty piece, U décolletage, wrap, bows, elbow length sleeves