Kate Middleton reacts to reunion with Prince Harry, Meghan Markle at Windsor Castle

Kate Middleton and Prince William stepped out with Prince Harry and Meghan Markle for a walkabout at Windsor Castle on Saturday, Sept. 10, much to the delight of the crowd that had gathered. While the reunion was certainly a surprise, the Princess of Wales thought it was only natural for them to come together after Queen Elizabeth II's death.

The "Fab Four" looked at floral tributes for the late monarch and also greeted well-wishers. According to The Telegraph, at one point the mum-of-three told a family that it was important for the four of them to get together to pay their respects to Her Majesty.

She said, "At times like this you've got to come together."

According to Fox News, Kate Middleton also told mourners about her youngest son Prince Louis' reaction when he learned that his great-grandmother had passed away. She said, "My little Louis, he's so sweet. He said, 'Mommy don't worry because she's now with great-grandpa.'"

She added, "This just shows you just how special she was to everybody, all generations...thank you for coming to pay your respects."

Queen Elizabeth II died at Balmoral Castle on Sept. 8 at the age of 96. Her husband Prince Philip passed away last year on April 9 at Windsor Castle. He was 99 years old.

Aside from the Princess of Wales, Prince William, Prince Harry, and Meghan Markle also thanked the people who waited outside the gates of Windsor Castle. The Duke of Sussex talked about his grandmother's home being a "lonely place up there now without her."

"Every room she was in, we felt her presence throughout," he said.

As for Meghan Markle, the highlight of her walkabout was when she shared a hug with a 14-year-old girl, who told reporters that she asked for the hug to make the duchess feel that she is welcome in the U.K.

Prince Harry and Meghan Markle were in the U.K. already when Queen Elizabeth II died. They are expected to join the funeral service on Sept. 19. But they may have to extend their stay after King Charles asked royal family members and royal household staff to observe a period of Royal Mourning for seven days after the funeral.