King Charles Makes Impromptu Appearance on 'American Idol'

American Idol judges Katy Perry and Lionel Richie performed at King Charles III and Queen Camilla's coronation concert in London Sunday, meaning they missed the live episode. Their majesties returned the favor by making a surprise appearance on the ABC singing competition. Ed Sheeran and Alanis Morissette joined Luke Bryan at the judge's table during the episode, which saw the field whittled down to the Top 5.

Richie and Perry appeared via video from Windsor Castle to let fans know why they weren't in Los Angeles. Then, King Charles and Camilla interrupted them, jokingly asking how long they needed the room for. They praised Perry and Richie's performances during the coronation concert and invited them to another party.

While nearly every part of the coronation ceremony was planned down to the second, the King and Queen's appearance on Idol came together quickly. "I have to tell you, I was driving in and my phone rings and it's the executive producer and she says, 'Well, we've got some news,'" host Ryan Seacrest told Entertainment Tonight after the episode aired. "I thought maybe something happened [with a contestant]. She said, 'Well, the king and the queen are going to make an appearance!'"

"I said, 'This is so great. How?' 'Well, I don't know. They're just gonna figure it out when Lionel and Katy are in some room in Windsor Castle,'" Seacrest continued. "So apparently, Lionel and Katy are staying overnight? Like, I don't know what's going on. They've got they've got separate wing," Idol showrunner Megan Michaels Wolflick added that it was "really fun" to put together the monarchs' appearance, even if it was also "intense."

Richie and Perry were invited to perform at the coronation concert because they have worked with King Charles in the past on charitable causes. Richie was the first Global Ambassador for the Prince's Trust, while Perry is an ambassador for the British Asian Trust and worked with UNICEF. Richie performed "Easy" and "All Night Long," while Perry got Princess Charlotte to sing along with her for "Roar." Perry also led the crowd in singing "Firework."

American Idol Season 21 is down to five contestants, Colin Stough, Iam Tongi, Megan Danielle, We Ani, and Zachariah Smith. Haven Madison, Warren Peay, and Oliver Steele were eliminated Sunday night. Sheeran joined the contestants for duets, singing "Perfect," "Thinking Out Loud," "Dive," and "Photograph." He also performed "Eyes Closed" solo. Morissette took the stage to perform "Thank U" and served as a guest mentor. Idol airs Sundays at 8 p.m. ET on ABC and is available to stream on Hulu Mondays.