The Instagram site British royal jewels has posted a very significant photo of Queen Mary wearing a large sapphire brooch which she used in her wing tiara as well as the Honeysuckle tiara now with the Duchess of Gloucester. The large sapphire brooch was later owned by Princess Margaret.
British royal jewels
https://www.instagram.com/p/Bs8d9HfHty1/ The site owner notes that the photo in question was found by the owner of the Jewelry of the Romanovs Instagram site
https://www.instagram.com/russian_treasure/?hl=en The photo in question shows Queen Mary at the laying of the foundation stones at Aberystnyth for the National Library of Wales on 15 July 1911 (Alamy is mistaken in saying the photo was taken on 11 July 1911)
This detail shows clearly that this brooch with its distinctive bows is the one which was used in the tiaras and was later worn by Princess Margaret
As British royal jewels notes this photo calls into question the provenance of both the brooch and the tiara and the many assertions that Queen Mary purchased the wing tiara and brooch from the estate of the Dowager Empress Marie.
I'll leave discussion of various issues to posters. But just a little more history about the occasion in 1911.
On 15 July 1911 George V and Queen Mary visited Aberystnyth to lay two foundation stones for the National Library of Wales.
For the occasion Queen Mary wore a pale blue dress
I wonder if this brooch was a coronation gift? Knowing that Queen Mary had owned the brooch since at least 1911 also makes sense of the entry in Hugh Roberts' book (page 164,footnote no 3) where he cites an entry in a Garrard's account dated 21 April 1914 for the making of the Gloucester Honeysuckle tiara which was designed to take the Cullinan V brooch, a large sapphire brooch and the pink topaz brooch.
Queen Mary in a much later photo with the tiara with the sapphire brooch
Congratulations to Jewelry of the Romanovs for finding the photo and thanks to British royal jewels for posting about it.