From Nemo65's photostream on flickr; upper corner fixed and spots removed with Photoshop and sepia tone removed by gogm.
Louise poses before a stage with a scene, possibly of Windsor Castle, in the background in this Mayall photo from 1 March 1861.
Keywords: 1861, Mayall, Princess Louise, Princess, Hanover family, Sutherland family, British, straight coiffure, feathered hat, high neckline, jacket bodice, bows, puffed sleeves, shallow vee waistline, Swiss belt, crinoline, over-skirt, neck band, bracelets