This is great, Lynn! That collection of old photos was quite a find. Thanks for sharing your research.
I have photos of Mary's grave and house in Biarritz, if you're interested. Her villa is still there and lived in by the the descendants of Mary's housekeeper/companion, who inherited her estate.
The name "Mary Cannan"on the tombstone is hardly decipherable because the family who inherited her estate took over the plot for their own dead members, and have now probably forgotten who Mary Cannan was.