Princess Kate, 41, watched the service from the balcony of the Foreign and Commonwealth Office building as the King led the royal procession, followed by her husband Prince William, Prince Edward and Princess Anne.
The poignant day typically sees the Princess recycling one of her formerly-worn black outfits in a bid to not distract from the true meaning of the occasion. On Sunday, the royal did just that, slipping into an Alexander McQueen coat dress previously worn at the Remembrance Day Service in 2019.
The striking coat was a fitting choice for the Princess, due to its military-style feel and embellished braided trims on the bodice. She pinned a poppy and Fleet Air Arm brooch to its lapel; Kate was made Commodore-in-Chief to the Fleet Air Arm by her father-in-law King Charles in August.
The mother-of-three swept her brunette tresses into a neat, low bun, adding an exceedingly smart hat adorned with plumes of black felt coiled into a beautiful bow.
Kate's headwear was another re-wear. The then-Duchess of Cambridge wore the hat to the Remembrance Day Service in 2017 during her pregnancy with Prince Louis, and at Prince William's graduation from Sandhurst in 2006 before they were married.
Most alluring, however, were the Princess' breathtaking cluster pearl earrings, which Kensington Palace confirmed formerly belonged to the late Queen Elizabeth II.
Since stepping into her more senior royal position as the Princess of Wales, we have seen far more of Her Late Majesty The Queen's jewellery being brought into the royal spotlight as Kate wears several of her most precious pieces.
The debut of Kate wearing the Queen's spellbinding earrings comes after the royal appeared to be wearing Queen Elizabeth's three-strand pearl necklace at The Royal British Legion Festival of Remembrance on Saturday night.
The sharing of jewellery was something the late Queen widely encouraged while she was still alive, and she trusted the Princess of Wales with some of her most prized jewels during her reign.
Back in 2014, the Princess attended a black-tie reception at the National Portrait Gallery wearing the Nizam of Hyderabad necklace. Donning a midnight-blue Jenny Packham dress for the occasion, Princess Kate embellished her outfit with the multi-million-pound platinum and diamond necklace personally lent to her by the Queen - estimated to be worth £66.3 million.
The Princess of Wales remains the only royal lady to have worn the Nizam of Hyderabad piece besides Queen Elizabeth.
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