The Queen's Platinum Jubilee is now all wrapped up and the ceremonies are over, but mysteries and little-known secrets are still coming to light - from lip readers' insights to family tensions being leaked.
And it turns out there was a secret hidden in the monarch's outfit, as on Sunday she donned a chic green coat with a distinctive black pin in her hat, as Hello! Reports.
Many were left bemused by the pin, wondering why it was there and what its purpose was - was it strictly decorative, or did it serve a function?
It turns out the black fastener was actually a mourning pin, and was the Queen's way of paying tribute to her late husband, Prince Philip, during the remarkable four-day celebration of her Platinum Jubilee.
What did you think the pin was? Let us know in the comments...
The Queen wore the pin during her final appearance on the Buckingham Palace balcony.
The black mourning pin was placed at the front and centre of her hat, contrasting against the elegant emerald green that matched her coat.
She also wore pearl earrings, a matching necklace and white gloves.
Her Majesty rounded off the look with a diamond bow brooch, which is also meaningful. It carries a long family history and is one of a trio in different sizes with the same design that the Queen has worn on poignant royal occasions.
However, it was her mourning pin that took centre stage. During most of her 70-year reign, the Queen was supported by Prince Philip, who died aged 99 on 9 April 2021. Mourning pins tend to be worn by members of the royal family following a death.
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The day before, Prince Charles remembered Prince Philip in an emotional speech given at the Party at the Palace after show-stopping performances from music legends like Sir Elton John, Rod Stewart and Alicia Keys.
In a touching moment, Charles spoke of his "much missed" late father, calling him, "My Papa" and saying the Queen's late husband Philip was there "in spirit".
He said: "Your 'strength and stay' is much missed this evening but I am sure he is here in spirit... "My Papa would have enjoyed the show and joined us wholeheartedly in celebrating all you continue to do for your country and your people."
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