Regards,
Dave.
The Lady-in-Waiting is Lady Elizabeth Cavendish, the daughter of the 10th Duke and Duchess of Devonshire (who was the Queen's Mistress of the Robes) ! While I initially thought that she might be wearing one of the Tiaras from the Devonshire Parure, it appears that this one is her mother's Sapphire Necklace Tiara, HERE !
The Sapphire Necklace Tiara was worn by Lady Elizabeth for later Tours and since its fate is unknown it is possible it might have been inherited by her. Interestingly, Sotheby's is auctioning a few of her belongings this month, but there are no notable jewels except a diamond bracelet.
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