Prince William and Kate Middleton make surprise appearance after King Charles' coronation
King Charles III was honored by Prince William during his coronation ceremony on May 6
{{#rendered}} {{/rendered}}Prince William and wife Kate Middleton made an unexpected appearance Sunday as they prepared for King Charles' coronation concert.
The Prince and Princess of Wales surprised a group of locals who had gathered for a Big Lunch – a street picnic intended to bring United Kingdom communities together in celebration.
Appearing at the Long Walk outside Windsor Castle, Kate wore a casual look. The princess paired a light blue blazer with a white top and black pants while William donned a navy blue suit.
{{#rendered}} {{/rendered}}Princess Kate's dressed-down look was completed with white sneakers.
Kate Middleton and Prince William appeared at a Big Lunch in a casual look. (Getty Images)
Prince William and Kate Middleton surprised locals at the Long Walk outside Windsor Castle. (Reuters)
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Prince William and Kate Middleton spoke with the crowds of people who attended a Big Lunch outside of Windsor Castle. (Reuters/Stephanie Lecocq)
"It was a lovely family atmosphere," an observer told People magazine. "William and Kate were really relaxed straight from the get-go. They were posing for selfies and talking to kids wearing crowns."
{{#rendered}} {{/rendered}}The insider said the Big Lunch was a "great party."
"As soon as word went around that they were there, people descended onto the area around the Long Walk."
Princess of Wales Kate Middleton poses for a selfie at a Big Lunch. (Andrew Matthews/Pool via Reuters)
The Royal Family Twitter account shared photos from the event.
{{#rendered}} {{/rendered}}"Wonderful to see so many people out enjoying their #CoronationBigLunch today!" the photos were captioned.
As did the Prince and Princess of Wales.
They shared multiple photos showing the crowds of people who flocked to The Long Walk at Windsor.
{{#rendered}} {{/rendered}}One photo showed William crouched down speaking with children at the event, while another showed Kate shaking hands and posing for pictures.
First lady Jill Biden also attended a Big Lunch in London following Charles' coronation. She attended the coronation while President Joe Biden remained in the U.S.
Jill and her granddaughter attended the lunch alongside Prime Minister Rishi Sunak.
{{#rendered}} {{/rendered}}Jill Biden and Britain's prime minister share tea. (Getty Images)
Jill Biden and granddaughter Finnegan Biden share cake with Prime Minister Rishi Sunak during a Big Lunch at Downing Street. (Christopher Furlong/Getty Images)
The king's nieces, Princess Beatrice and Princess Eugenie, the daughters of Prince Andrew, also attended a post-coronation lunch.
Princess Beatrice of York and Princess Eugenie of York pose for a selfie as they attend a Coronation Big Lunch in Chalfont St Giles, Buckinghamshire on May 7. (WPA Pool/Getty Images)
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King Charles walks in the coronation procession following his ceremony at Westminster Abbey on May 6. (Richard Pohle/Pool via Reuters)
Despite William and Kate's surprise appearance, King Charles and Queen Camilla were not expected to attend any Big Lunches in London. The royal couple will be at the coronation concert Sunday evening, where Prince William will honor his father with a speech.
{{#rendered}} {{/rendered}}The royal couple's appearance follows King Charles' coronation, where 2,000 guests watched him officially become His Majesty. Charles and his wife Queen Camilla were crowned in a two-hour ceremony at Westminster Abbey.
Prince William and Kate attended the ceremony in royal regalia and the princess wore a custom Alexander McQueen dress for the occasion. The designer also created Kate's bridal gown.
Kate Middleton and Prince William attend King Charles' coronation. (Getty Images)