For the tour Princess Margaret was accompanied by Lady Elizabeth Cavendish, the 11th Duke of Devonshire’s sister, as an extra lady-in-waiting, wearing the Devonshire honeysuckle tiara in the photo, and her regular lady-in-waiting, Iris Peake, eldest daughter of Viscount Ingleby.
Iris Peake’s youngest sister Mary Rose might have worn the same tiara for her wedding to Everard March Phillipps de Lisle in 1959. The Ingleby title was created for their father in 1956. Their mother was a daughter of the 7th Earl of Essex. The tiara possibly comes from this side of the family.