When I saw the photo below, I had to read the caption again to make sure I was not seeing things!
For the 21st birthday celebrations of her son, the Earl of Shrewsbury, Lady Ingestre wore the Anglesey tiara.
Lady Ingestre, nee Winifred Paget, was the sister of the then Marquess of Anglesey. After her first husband died in 1915 Lady Ingestre married Richard Pennoyer, then in the US Diplomatic service, in 1917.
Whether on re-marriage she lost access to the Shrewsbury jewels or whether she choose not to wear them for her son's 21st birthday celebrations because he was about to announce his engagement is something I don't know.
At the celebrations the Marchioness of Anglesey wore another jewel.
Other notable tiara wearers included
Lady Litchfield
Lady Pembroke
Lady Ilchester second from the left