These are two legendary beauties of the day, Lily Elsie and Lady Diana Cooper, née Manners, daughter of Violet Lindsay Manners, Duchess of Rutland. Lady Diana became a noted actress and author, but I cannot find photos of her dating from before 1920 other than this one. Her article in thepeerage is here.
From wfpp.cdrs.columbia.edu/pioneer/ccp-lucy-duff-gordon/ via Pinterest search; enlarged one quarter and removed monocolor tint.