Her article in theperage is here. The article has a smaller version of this portrait that they date to 1785.
From blog.daum.net-kmozzart-7152.
Frances Mary wears a cape fringed with bands of cloth matching those framing her décolletage in this early 1780s Romney portrait.
Keywords: Romney, Frances Mary Harford, Frances Mary Wyndham, Calvert family, Wyndham family, British, straight coiffure, , cap, modesty piece, vee décolletage, bertha, cape, choker necklace