Apologies for this, non royal fashion related,but
Don't apologize for bringing up Lady Pamela. I would say she is definitely pretty high on the royalty scale, actually with more "royal blood" than Beatrice or Eugenie. I recommend her memoir, Daughter of Empire: My Life as a Mountbatten. Among other interesting things, she was with the Queen in Africa when word came that George VI had died.
There was a documentary a few years ago in which she and India both showed and talked about the dresses that they wore as bridesmaids, India for Diana, and Pamela for then Princess Elizabeth.