Queen Elizabeth II did not attend King Charles and Queen Camilla's wedding ceremony, and royal fans are just learning the reason why.

Charles and Camilla mark their 20th wedding anniversary today (Wednesday, April 9) and are spending the day in Italy on a state visit. This morning, a video was posted to the official Royal Family X account marking the couple's two decades years together.

The caption of the video read: "20 Happy Years!" along with a white heart emoji. Similar clips have been shared to social media platforms as fans share their well-wishes with the current king and queen.

"Wishing King Charles and Queen Camilla a HAPPY 20th WEDDING ANNIVERSARY!" one person wrote on X.

A TikTok user, however, commented: "Queen Elizabeth and Prince Philip did not attend King Charles' wedding to Camilla."

The Queen and and Prince Philip were not present for the civil wedding ceremony at the Windsor Guildhall. Only 28 people attended, including Prince William and Prince Harry and Camilla's children, Tom and Laura Parker-Bowles.

A palace spokesperson said of the Queen's absence at the time: "The Queen decided not to attend the civil ceremony at Windsor's Guildhall because the couple wanted to keep the ceremony low-key and her presence would not allow that to happen."

However, However, autobiographer Robert Hardman later claimed Her late Majesty's choice not to attend stemmed from a "disapproval of the arrangements" but "not of the marriage itself."

The Queen did attend a Service of Prayer and Dedication for the wedding at St George's Chapel, where she was a guest of honour.

She and Prince Philip also hosted a reception at Windsor Castle following the ceremony, where she wore white.

Charles and Camilla's anniversary coincides with the couple's first state visit to Italy since they came to the throne, with the pair having landed in Rome on Tuesday (April 8).

The Royal Family's X account shared a post to mark the occasion, featuring two new photos of the pair.

"As we begin our first visit to Italy as King and Queen, we are so looking forward to celebrating our twentieth wedding anniversary in such a special place – and with such wonderful people," the post read. "A presto, Roma e Ravenna!"