Queen Elizabeth II has also opted to wear the piece to mark a number of special events.
She wore the brooch in portraits released to mark her 50th birthday, and at the funeral of Lord Mountbatten in 1979.
The Queen is thought to have nearly 100 brooches in her extensive collection.
The royal is rarely seen in public without a historical brooch pinned to her outfit.
The royal line of succession - who outranks who?
The line of succession to the British throne dictates the order in which each member of the Royal Family would ascend to the throne.
It is also seen as a ranking of importance with the head of the line, the Queen, taking the place of ruler.