Royal etiquette can be confusing for those who aren’t used to attending palace events, and even though Dame Helen Mirren once played Queen Elizabeth on the big screen, she found herself tongue-tied around the late Queen and Prince Philip in real life.

In a new interview with the “Today” show, Mirren shared a story about a time she was invited to an event with the Royal Family. The actress explained that after she’d been served tea, she looked around for milk, but the jug was out of reach.

"The milk jug is on the other side of Prince Philip ,” Mirren recalled. “I’m thinking, ‘How do I get the milk?’ And I just could not remember how to…what’s the word…address Prince Philip.”

Helen Mirren shakes hands with Queen Elizabeth at a reception in 2014.

(Image credit: Getty Images)

In case you're wondering, the correct answer would be "Your Royal Highness" when first greeting him, and "sir" thereafter. But Mirren was stuck. "Do I call him sir? Is it Your Majesty? Is it Your Royal Highness?…