Queen Elizabeth II's death on Thursday marked a historic change in titles and roles within the royal family as the newly-appointed King Charles III named his firstborn son, William, and wife Catherine the Prince and Princess of Wales.

Their amended names also come with adjusted appointments, and marked a "new era" for the palace as a royal expert exclusively told Fox News Digital that after more than seven decades under Her Majesty's rule, the family is wading into "unchartered territory."

"The way we have known William and Kate and Charles and Camilla, those are bygone days," Shannon Felton Spence, former British Public Affairs official, said. "It is a new era." 

QUEEN ELIZABETH II'S COFFIN ARRIVES IN EDINBURGH, SCOTLAND

Queen Elizabeth II with Prince William and Kate Middleton

Queen Elizabeth II's death on Thursday marks a "new era" for the palace as roles change for Prince William and Kate (pictured in 2019,) along with King Charles III and Queen Consort Camilla. (Geoff Pugh)

"William was supposed to join UNGA (United Nations General Assembly) in two weeks, but won’t do that now," Spence noted. "They were also supposed to do another visit to the US this year, who knows if that happens." 

William and Catherine, who were named the Prince and Princess of Wales by King Charles III on Friday, were previously known as the Duke and Duchess of Cambridge.

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"Regardless of the timing, they all have different roles now," Spence said. "The Cambridges have shifted up. The things they were working on yesterday, they are no longer working on, they have new [duties.]"

Queen Elizabeth II Kate Middleton Prince William

Queen Elizabeth II smiled while standing on the balcony at Buckingham Palace in June to celebrate her Platinum Jubilee. (Max Mumby)

Prince Harry and his wife, Meghan Markle, will remain the Duke and Duchess of Sussex, but their children will now receive royal titles as Prince Archie and Princess Lilibet as they become sixth and seventh in line for the throne.

Kate addressed a group of children outside of Windsor Castle on Saturday as she said her youngest son was grieving the loss of his great-grandmother.

"My little Louis, he's so sweet. He said: 'Mommy don't worry because she's now with great-grandpa,'" the princess told members of the public mourning at the castle, according to a viral TikTok video. 

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"This just shows you just how special she was to everybody, all generations ... thank you for coming to pay your respects," Kate told the children as she addressed the large crowd of mourners for the queen.

Prince Harry Meghan Markle Prince William Kate Middleton

Catherine, Princess of Wales, Prince William, Prince of Wales, Prince Harry, Duke of Sussex, and Meghan, Duchess of Sussex on the long Walk at Windsor Castle arrive to view flowers and tributes to Queen Elizabeth II. (Chris Jackson)

Prince Philip died in April 2021 at the age of 99. He and Queen Elizabeth had been married for 73 years.

In Friday's sovereign address, King Charles III said he was "proud" to give the titles to William and Catherine, and added they will "continue to inspire and lead our national conversations, helping to bring the marginal to the centre ground where vital help can be given."

He also added, "I want also to express my love for Harry and Meghan as they continue to build their lives overseas."

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