From the museum's Web site.
The sleeves of Lady Ottoline’s dress appear to come from the middle 1500s (before grotesque puffing) and her dress has a partlet and split bodice.
Keywords: 1912, de Meyer, Ottoline Morrell, Cavendish-Bentinck family, Morrell family, British, straight coiffure, wavy coiffure, partlet, high neckline, lace, split bodice, sweetheart décolletage, rolled sleeves, long close sleeves, close skirt, necklace, earrings