Why Kate Middleton and Prince William Didn't Attend King Charles' First State Opening of Parliament

Prince William appeared beside his father last year for the event

Kate Middleton and Prince William weren't by King Charles' side for a first of his royal reign.

On Tuesday, King Charles and Queen Camilla attended the State Opening of Parliament for the first time since his accession. The King wore the Imperial State Crown for the first time since his coronation and read the King's Speech, which was written by the government and contained an outline of its proposed legislation for the new parliamentary session.

Aside from the King and Queen, Princess Anne took part in the event in her role as Gold Stick in Waiting.

However, the Prince and Princess of Wales didn't attend the historic event.

Related: Queen Camilla Makes Her Debut in a Historic Crown for King Charles' First State Opening of Parliament

It's not required for the heir to the throne to attend the State Opening of Parliament, but King Charles accompanied his mother, Queen Elizabeth, several times throughout her reign. He attended for the first time in 1970.

But Prince William had a significant event of his own on Tuesday: the Earthshot Prize awards ceremony in Singapore. The Prince of Wales, 41, hit the green carpet alongside Cate Blanchett, Hannah Waddingham and Sterling K. Brown as they honored the next wave of environmentalists coming up with answers to the planet's most pressing problems.

Although Princess Kate, 41, joined her husband at the inaugural awards ceremony for the environmental prize in London in October 2021 and for the second cycle in Boston in December 2022, she did not make the trip to Singapore. She stayed in the U.K. to support their son Prince George as he tackles school exams.

“Catherine is very sorry she can’t be here,” Prince William said in Singapore this week. "She is helping George through his first set of major exams.”

Related: Prince William Hits the Green Carpet in Singapore for His Earthshot Prize Awards

In May 2022, Prince William was present at the State Opening of Parliament for the first time. Buckingham Palace announced that the Queen, who died in September 2022 at age 96, would miss the event due to "episodic mobility problems." For the first time, Charles represented his mother and read the Queen's Speech.

Queen Elizabeth delegated her royal duty of opening a new session of Parliament to her son and grandson via a letter patent, which enabled them to jointly exercise that function. Both were acting as Counsellors of State, and two Counsellors of State are required to perform any of the monarch's constitutional duties.

Princess Kate has not yet attended the State Opening of Parliament.

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King Charles, 74, and Queen Camilla, 76, may not have been accompanied by Prince William and Princess Kate for the State Opening of Parliament, but the monarch has made his son and daughter-in-law's important roles within the royal family clear. He gave them the titles of the Prince and Princess of Wales just one day after his accession, and they've been at prominent events — including being the only other royals at the coronation celebrations in Scotland over the summer.

“Charles is leading the way for them already, and [William and Kate] are both involved in decision-making behind the scenes. They are ready and willing to do the job — and Kate is very much a part of that,” a friend of the princess previously told PEOPLE.

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