“It is said that the elegant leaves represent strength, stubborn resistance and enduring power,” Tobias explained.

He added: “When the Queen received this beautiful gift all those years ago, she may not have seen that those are qualities she herself would become known and loved for.

“But on reflection, what better symbol could there be to celebrate the Queen’s character?”

In 2014, the brooch was loaned to Kate Middleton for the first time for her tour of New Zealand and Australia with the Duke of Cambridge and son Prince George.