I have no ides which Lady Pakenham this is.
From Paul Frecker; sepia tone removed (and re-added only to border) with Photoshop and the image size increased by half by gogm.
The day of the dome crinoline is slowly ending - this is a half dome crinoline. Her sleeves are full, almost puffed, but not pagoda or flared sleeves.
Keywords: 1862, Silvy, British, hurluberlu coiffure, high neckline, collar, long full sleeves, cuffs, crinoline, neck band