I don't have an ear for accents either. There always seems to be someone finding an actor's accent that's not their own wrong. She's from England I read today according to imdb.com. Although she's been living in the US for almost twenty years now.

At first I thought Arthur was just a name they pulled out of nowhere, but then I went to gateworld and someone suggested it was from HitchHiker's Guide to the Galaxy. In the book the main character's name is Arthur and he travels in space in his pajamas. And well, John travels in space and he was wearing his pj's. :D