I played around with darkening the image to bring out details blanched out in the original. This image was darkened as far as I could without obscuring Mac's fur.
Toria's dress has clean lines suggesting this photo was taken after 1910. Heavy darkening suggests her blouse or undergarment ends just about 5 cm below her necklace and has three visible horizontal bands each about 3 cm wide.
Keywords: Princess Toria, Welf family, Wettin family, Princess, British, straight coiffure, trapezoidal neckline, long close sleeves, cuffs, lapels, close skirt, necklace