1861 (18 February) Lady Harriet Spencer-Churchill and Jane Spencer-Churchill by Camille Silvy
An article about Harriet that lists daughter Jane in thepeerage can be found here. National Portrait Gallery, London has a Silvy photo dated 18 February 1861 "Harriet Louisa Hester (née Gough-Calthorpe), Lady Alfred Spencer-Churchill (1832-1901), Wife of Lord Alfred Spencer-Churchill; daughter of 4th Baron Calthorpe" that is not posted to their Web site. It could easily be this photo. The date assigned in the title of this image is based on assuming that photo and this one are the same.
From Paul Frecker; sepia tone removed (and put back in frame) by gogm.