Princess Anne Made Brother King Charles Laugh After His Coronation with This Nickname

Princess Anne and King Charles proved that good-natured sibling ribbing never takes a rest.

In behind-the-scenes footage from the new BBC documentary Charles III: The Coronation Year, which aired in the U.K. on Tuesday and was circulated on X (formerly Twitter), the royal family had just returned to Buckingham Palace following the coronation on May 6. Princess Anne walked into a room where King Charles was surrounded by courtiers.

"Hello, Old Bean," the Princess Royal said to her older brother, prompting him to laugh. King Charles then took Princess Anne's hand and kissed it.

Behind King Charles, a TV screen showed crowds moving down The Mall in London toward Buckingham Palace, where they'd catch a glimpse of the royal family when they appeared on the balcony for a flypast.

Princess Anne, 73, played a prominent role in the coronation, taking part in the Coronation Procession following the crowning ceremony at Westminster Abbey as the "Gold-Stick-in-Waiting." The prestigious position, which Princess Anne has held since 1998, dates back to the 15th century when two officers, a Gold Stick and a Silver Stick, were placed close to the monarch to protect them from harm.

Queen Elizabeth and Prince Philip's only daughter rode on horseback behind King Charles, 75, and Queen Camilla, 76, in the Gold State Coach as they made their way from Westminster Abbey to Buckingham Palace. Princess Anne led 6,000 armed services personnel through the streets of London in the procession. While many members of the royal family participated in the parade by riding in horse-drawn carriages or cars, Princess Anne was the only royal to ride on horseback.

In an interview with CBC News that aired ahead of the coronation, Princess Anne joked about the perks of the job.

"I have a role as the Colonel of the Blues and Royals in the Household Cavalry regiment as Gold Stick [in Waiting]. And Gold Stick was the original close protection officer. So that is a role I was asked if I'd like to do for this coronation, so I said yes," she said. "Not least of all, it solves my dress problem."

Can't get enough of PEOPLE's Royals coverage? Sign up for our free Royals newsletter to get the latest updates on Kate Middleton, Meghan Markle and more!

To mark Princess Anne's birthday in August, King Charles shared a never-before-seen photo of them from the coronation day. The newly crowned King beamed in the Imperial State Crown and Robe of Estate, while uniform-clad Anne looked sharp in her uniform, complete with feathered cap.

The BBC documentary captured intimate moments behind-the-scenes of the crowning ceremony, including King Charles poking fun at his "sausage fingers" as Prince William practices tying a robe on him and the family practicing for the big day at Westminster Abbey.

BBC described the film by saying, "With unrivaled insights from many of those involved, as well as moments of great poignancy and humor, this film gives a unique perspective on the inner workings behind a defining moment which marks a new era in the history of the monarchy."