This is a proper castle, then! From some world where royal titles and things mattered and meant something. Arthur is of course familiar with castles, he's from England, but they're historic sites or private residences. No one rules from them. He's not even sure if the royal family does any actual royal things anymore. The Queen had been on the radio sometimes in the early days of the war, but Churchill had been on a whole lot more. And other people he can't remember at this point, as he'd been a small child.

This is like something out of the stories his mother had read him and Percy. Not just visually, but the way Jon describes it. The names mean nothing to Arthur, but he can assemble the general context easily enough. One royal family got bullied by another royal family until they said 'fine, you can be in charge-in charge of everything' and then decided they didn't like that idea. He's reasonable certain history is full of that sort of thing.

"Quite impressive!"

The Empress ambles over to the fire and flops down in front of it with an impressive thud. Arthur takes a seat at the table, looking about him with interest. Yes, this is most certainly a working castle from a different time.

"I grew up on a little chain of islands, not much in the way of castles. A couple of old forts, but they're....not in good shape."

That's on way of putting it.