Here is the only pic of Lady Brigid with her tiara that I know of.
According to Royal Musings the tiara was also worn by the bride of her eldest son, Hon. Victoria Mancroft. But I have never seen a picture of her wedding.
Princess Antonia did not wear her mother’s tiara but the tiara from her husband’s family. And her daughter-in-law Jemma Kidd did not wear a tiara at all.
Princess Victoria Augusta once wore this tiara for a photo shoot. I think that it was done for a magazine, and the magazine also provided the tiara.