The King struggled to hold back tears as he attended the Palace of Westminster to receive addresses from both Houses of Parliament in Westminster Hall.
King Charles, accompanied by the Queen Consort, was addressed by the Speakers of each house, with the King replying afterwards. During the singing of the National Anthem, the new monarch was overcome with emotion.
As the singing continued, King Charles was fighting back tears.
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Sir Lindsay Hoyle, who has served as Commons Speaker since 2019, offered "our heartfelt sympathy" to King Charles and the royal family in his speech, before recalling the many occasions in which the Queen visited Westminster Hall.
In particular, the Commons Speaker recounted the time the Queen visited the oldest building in Parliament to celebrate the 300th anniversary of the Glorious Revolution, before joking: "It is perhaps very British to celebrate revolutions by presenting an address to Her Majesty."
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The Glorious Revolution permanently established Parliament as the ruling power of England and, later, the United Kingdom, representing a shift from an absolute monarchy to a constitutional monarchy. King Charles, who was sat on a throne next to his wife, the Queen Consort, appeared to smile after the mention of the events which led to the deposition of James II.
The Commons Speaker told Westminster Hall: "On other occasions, our late Queen was here to mark the historic moments, such as the 50th anniversary of the Second World War, a war in which she herself served in the armed forces.
"And in 1988, we celebrated the 300th anniversary of the revolutions of 1688 to 1689. It is perhaps very British to celebrate revolutions by presenting an address to Her Majesty. But those revolutions led to our constitutional freedoms, set out the foundation for a stable monarchy, which protects liberty."
Sir Lindsay also told the King he has taken on "weighty responsibilities". He went on: "We know you hold the greatest respect, the precious traditions, the freedoms, and responsibilities over our unique history and our system of parliamentary government.
"We know that you will bear those responsibilities which fall to you with the fortitude, dignity, demonstrated by Her late Majesty."
Lord Speaker Lord McFall of Alcluith also delivered an address to King Charles, in which he paid tribute to the Queen's "inspiring reign of deep and unparalleled devotion" and pledged loyalty to him on behalf of the House of Lords.
He said: "Her late Majesty, our treasured Queen and your beloved and deeply missed mother came here to Westminster Hall many times to receive the congratulations of her loyal subjects in the two Houses of Parliament and to celebrate with them historic landmarks and her long life of dedicated public service.
"She was both a leader to and a servant of her people. Her humility and integrity commanded the respect and captured the imagination of peoples and nations across the globe."
At the end of their speeches, both Speakers delivered a humble address, unanimously agreed by MPs and peers, which conveyed "deep sympathy" to the King and his family for their loss, paid tribute to the late Queen for her "unstinting dedication" and "untiring endeavours", and expressed the Houses' "loyalty" to the King.
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