Thank you all for your helpful comments & Sylvia, thanks so much for tidying up a very special photo.
We now are quite certain that it is G grandmother, Lydia, b.1858. which would mean she was about 21 when the original photo was taken, maybe around the time of her marriage in 1879. The only problem is, she died in 1948. So, China, I am thinking it may have been done as a keepsake for my grandfather when he went away to school or later when he joined the navy. He left home in Dorset when he was 11years old, went to Greenwich Hospital School & subsequently joined the R.N. He left England in 1913, never to return.
I am interested in your comments about her appearance, Wiggy. I just had an email from a distant cousin, (descended from this lady's sister) who thought the same & was intrigued by the beads & wondered if there may have been a Romany connection. However, she has heard from her G grandmother That she had Spanish heritage. Neither of us has turned up anything vaguely Spanish, but this lady's mother was 'base born' So, perhaps my 3x G Grandfather was a Spaniard. I guess we will never Know?
I have hopefully attached a photo of Lydia (cropped from a family photo, taken around 1900), we are fairly certain it is the same lady. I think in this photo she looks a bit like she has been upholstered.