King Charles leaves Denzel Washington stunned

American actor and director Denzel Washington had an unforgettable encounter with British King Charles at the Royal Film Performance of Gladiator II.

The award-wining actor shared said he ‘didn’t Know’ the right way to greet the King at the premiere in London on Wednesday.

The monarch made a solo appearance at the ODEON Luxe Leicester Square a day before his 76th birthday. The King met the movie's cast members, including Washington.

In the Video footage from the event shows the 69-year-old actor shaking the King's hand as he tells him, "I didn't know if I was supposed to grab you or not, but it's my pleasure."

There are no obligatory codes of behavior when meeting the Queen or a member of the royal family, but many people wish to observe the traditional forms.

"For men this is a neck bow (from the head only) whilst women do a small curtsy. Other people prefer simply to shake hands in the usual way," according to the royal family's website.

The confusion didn't cause any issues, as Washington, who plays gladiator trader and arms dealer Macrinus, could later be seen smiling as he described his character to the King.

"I’m ... just awful … I’m a lovely man you’ll see. I’m a lovely chap and doing my best," he said.

"You've been in so many films, it's fantastic," King Charles was heard telling him in response.

The actor gushed over the King after his brief but vibrant interaction with the monarch who seemingly put him at ease with his admirable gestures at the star-studded event.