King Charles and Queen Camilla are spending her birthday at work with the State Opening of Parliament.

On July 17, coinciding with the Queen’s 77th birthday, the royal couple marked the formal start of the new parliamentary session. It comes just weeks after the Labour Party won the July 4 general election, making Kier Starmer the U.K.’s new prime minister.

Armed forces lined London’s streets for the procession from Buckingham Palace to the Houses of Parliament. King Charles, 75, and Queen Camilla traveled in the horse-drawn Diamond Jubilee State Coach, and the royal regalia — the Imperial State Crown, the Great Sword of State and the Cap of Maintenance — traveled in their own carriage, Queen Alexandra’s State Coach.

King Charles salutes as he leaves Buckingham Palace for the State Opening of Parliament on July 17, 2024.

Shortly after arriving at around 11.15am, King Charles — in his uniform of Admiral of the Fleet Royal Naval Number 1 Dress with cap and sword — made his way into the Palace of Westminster through the Sovereign’s Entrance, where he was met by the Lord Great Chamberlain before heading to the Robing Room. There, he dressed in the Parliament Robe of State and the Imperial State Crown.

Camilla wore the George IV State Diadem.

King Charles III and Queen Camilla arrive for the State Opening of Parliament, at the Houses of Parliament, in London, on July 17, 2024.

During the ceremony, King Charles delivered the King’s Speech, written by the government to outline its policies and proposed legislation for the new parliamentary session. Taking around 20 minutes, he had completed the speech by 11.50am U.K. time.

Queen Camilla as she traveled down the Mall from Buckingham Palace for the State Opening of Parliament on July 17, 2024.

He and Camilla then made their way back to the Robing Room.

The event is full of rich tradition, starting with the royal bodyguards doing a ceremonial search for explosives in the cellars of the Palace of Westminster. This commemorates the failed “gunpowder plot” of 1605 when English Catholics conspired to blow up the Houses of Parliament and Protestant King James I. Another tradition includes a Member of Parliament being held “hostage” in Buckingham Palace during the event to ensure the monarch’s safe return.

The Imperial State Crown is carried into the Houses of Parliament on July 17, 2024.

King Charles led the first State Opening of Parliament ceremony of his reign in November 2023. The event marked his second time wearing the Imperial State Crown, six months following his coronation in May 2023. Although he was officially crowned with the St. Edward’s Crown, used only to crown a new king or queen during the coronation, he swapped it for the Imperial State Crown toward the end of the service and appeared in it on the Buckingham Palace balcony and in official portraits from the day.

The Yeomen of the Guard on duty at the House of Lords, where the King’s Speech took place on July 17, 2024.

He was joined by Queen Camilla, who sported the historic Diamond Diadem for the first time at the event. The regal headpiece made with 1,333 diamonds was created for the 1820 coronation of King George IV and is what the monarch wore (along with a large purple velvet cap) on his way to Westminster Abbey for his crowning ceremony. Since then, the diadem has been worn by every British queen, reigning or consort: Queen Adelaide, Queen Victoria, Queen Alexandra, Queen Mary, Queen Elizabeth (the Queen Mother) and Queen Elizabeth.

Queen Camilla also recycled her coronation gown for the first State Opening of Parliament of her husband’s reign.

King Charles and Queen Camilla at the State Opening of Parliament on Nov. 7, 2023.

King Charles first attended the State Opening of Parliament in 1970 and appeared at the event several times supporting his mother. He memorably stepped in for Queen Elizabeth at the ceremony in May 2022 after Buckingham Palace announced that the Queen would miss the event due to “episodic mobility problems.” For the first time, Charles represented his mother and read the Queen’s Speech.

Can’t get enough of PEOPLE’s Royals coverage? Sign up for our free Royals newsletter to get the latest updates on Kate Middleton, Meghan Markle and more!

King Charles and Queen Camilla’s appearance at the State Opening of Parliament continued their busy week, as the couple spent July 15 and July 16 visiting the Channel Islands.