Billy Eichner at the European premiere of "The Lion King" in London.
Billy Eichner "started freaking out" over royal protocol when he met Prince Harry and Meghan, Duchess of Sussex, at "The Lion King" premiere on Sunday.

The 40-year-old actor voices Timon in the new live-action version of the classic Disney animation, and got the chance to meet the royals - who have two-month-old son Archie together - at the European premiere in London over the weekend.

But after a video surfaced online of Billy on the red carpet telling his co-star Seth Rogen - who voices Timon's best friend Pumbaa - what he was planning on saying to Harry and Meghan, he's now said the list of protocol he was given before the event had left him feeling confused.

Speaking during an appearance on Heart radio, he explained: "They give you a list of things you're supposed to do when you meet them. All this protocol, right. And it all sounds very formal and very old fashioned and very official, and we didn't know if people actually do it or not. And so when they started to approach, I just didn't know what I was going to say.

To which Seth added: "We were gauging what to do, we were just like ... Do you really say Your Royal Highness?"

And Billy continued: "That sounds crazy! Plus we're not from this country. And so when they finally started to approach, I thought 'Oh boy, I need to figure out what words are going to come out of my mouth'. And then I saw our co-star Keegan Michael Key and he didn't say Your Royal Highness, he didn't say anything! He just bowed his head slightly and shook Prince Harry's hand. And then I really started freaking out."

When the star did finally get to speak to the royals, he ended up chatting to Meghan - who was known as Meghan Markle before marrying Harry last year - about college, as they both attended the theatre programme at Northwestern University in Illinois.

In a separate interview for Capital Breakfast with Roman Kemp, he added: "We both went to Northwestern which is outside of Chicago which has a big theatre programme. And she was a theatre major, I was a theatre major and so when I met her the other night all we did is have this strange casual conversation about our acting teachers. Because we had some of the same acting teachers."