How King Charles Wished Prince Archie a Happy Birthday During Coronation Day

The newly crowned monarch toasted Prince Harry and Meghan Markle's son.

King Charles III shared a special birthday message for his grandson amid his historic coronation festivities

ET has learned that King Charles wished Prince Archie a happy birthday during a private family gathering for lunch on Saturday after his Coronation.

The well wishes came during a toast to those who were not in attendance. Prince Harry had been included in the lunch but left as soon as the service was over.

Archie -- the son of Harry and Meghan Markle -- turned 4 years old on Saturday, the same day as King Charles' royal ceremony. At the private gathering, King Charles reportedly raised a glass to toast those who couldn't be there, and wished Archie a happy birthday "wherever he was," the Daily Mail reports.

While Harry was invited to the gathering -- after previously not standing with his family on the balcony of Buckingham Palace -- he was not in attendance.

Instead, the youngest son of King Charles III departed Westminster Abbey immediately after the coronation of his father in a black BMW sedan and went straight to the airport, according to multiple reports. Harry was in attendance at the historic coronation but had zero interaction with his father or brother, Prince William

Journalist Omid Scobie told ET earlier this week that "people around [Harry] are working as hard as they can to find the quickest way into the country and the quickest way out." He added, "He's really only coming here for the ceremony, so any hopes for reconciliatory moments or private heart-to-heart between father and son or any of his family members, I think they'll be waiting for another time."

Harry also attended the coronation alone -- while his wife, Meghan Markle, and their two children -- Archie and 1-year-old daughter Lilibet, 1 -- remained at home in California. ET also learned that Archie’s birthday celebration consisted of a small gathering with friends and family in Montecito, California.

For more on the historic coronation, check out the video below.