Even before her accession to the throne, Princess Elizabeth had quite a nice collection of jewels, either presented by her parents for her birthdays or for Christmas, or presented to her for her wedding in 1947. When she became Queen in 1952, she gained access to the jewels labelled "Crown's heirlooms" or "Royal Collection" (minus the items retained until her death by the Queen Mother), and in 1953, when Queen Mary passed away, Queen Elizabeth II inherited the bulk of her grandmother's huge collection of jewels. So, if the Queen decided to wear the bottom part of Queen Mary's stomacher in 1956 for the review of Saint John's Ambulance Brigade, or in 1959 for the inauguration of the Saint Lawrence Seaway, it must have been a mere matter of choice and taste, and not because the Queen was at that time short on brooches...