Thank you Ashdean. Your comment made me realise that this tiara was not, as far as I can see, one of the items which Baroness Ravensdale's mother, Mary Leiter Curzon mentioned in her will.


Report of the will of Mary Curzon




A string of pearls sold by Bonhams in April 2013 is thought to have belonged to Mary Curzon and given to her daughter, Cynthia, at the time of her marriage to Oswald Mosley by Lord Curzon

https://www.bonhams.com/auctions/20622/lot/112/?category=list&length=96&page=2

Bonhams mentioned the possibility in this report
https://www.bonhams.com/auctions/20622/lot/111/