I posted my comment about an image being available for "Mary (Montgomerie) Lamb", 1783 - June 12, 1848. She was the mother of the 13th Earl of Eglinton in Scotland. The Future Museum does have a very stylized image of her done in watercolor. (See my previous post) It may be easier to go to PINTEREST
pinterest.com/pin/520236194428562240/
However, The Future Museum explains the image and the event, which was the talk of all Europe at the time.
I hope this clears up any confusion associated with others of the same name. ~(:-)