Prince William's hilarious quip to Gary Oldman during knighthood ceremony revealed

Prince William is one of several royals who carry out investiture ceremonies and he was back in action at Windsor Castle on September 30. The future King knighted Harry Potter and Dracula star Gary Oldman for his services to drama, officially making him Sir Gary Oldman from this point on.

The actor later spoke of being "humbled" by the experience and revealed that the Prince of Wales confessed to being something of a fan of his. He reportedly did this by sharing a good-natured joke with the actor during the "emotional" ceremony.

As per ITV News, the actor claimed that William told him, "I just want to give you a good wash", which isn't exactly what you might want to hear on such an important day! But it actually makes sense if you've seen Sir Gary in action in Apple TV's hit show, Slow Horses.

Gary was quick to joke back, responding, "Well, I think I’ve scrubbed up OK today."

His character in Slow Horses is often shown as unkempt and rude, and Prince William’s awareness of this indicates that he might tune in to the thriller when he’s not busy working. and, as it turns out, William is quite the fan of Gary’s other work too.

As per Town and Country, Sir Gary offered up more insight into his conversations with the Prince during the ceremony.

"He mentioned The Fifth Element and Churchill of Darkest Hour. He said he was very happy that I was here today and that it was him that had the opportunity to present me with [the knighthood]. He’s a fan, yeah," the star stated.

According to Gary, he and the Prince of Wales spoke for a minute, but the occasion was "very emotional" for the actor. Because of this, he confessed, "I almost couldn't find my voice."

He continued, "I think I feel very honored, very humbled and flattered, I think in equal measure. It compares to nothing else. It's a singular event, that is what it is. I thought the Oscar was a big deal. No disrespect to the academy, but it sort of pales in comparison to this. It's just been wonderful."

The actor was then given an extra honor from the Prince and Princess of Wales - earning a spot on their Instagram page in tribute to his knighthood.

Posting to their 17 million followers, the official account for William and Kate shared a photo of Sir Gary and wrote, "Thank you, Sir Gary Oldman, for decades of unforgettable performances - whether as hero or villain, or something in between! Not bad for a Slow Horse..."

Other recipients of honors at the investiture ceremony included English actress Samantha Morton - best known for roles in television shows like The Walking Dead and the Oscar nominated movie, The Whale - who was made an Officer of the Order of the British Empire (OBE) for her services to drama and charity.