1 Alice: Well, thank you Dr Jones. I know you've tried your best. It's clearly a difficult cipher.
2 {Alice leaves}
3 Monty: Was she being patronising to me?
4 Prof. Jones: I don't know. I was too busy being unimpressed by your lousy decoding skills.

On reflection, it's a bit rude that none of them offered to show Miss Thoroughgood out of the museum building. Although evidently she knew her way to this office, so she should know her way out again.

Yes, that's a suit of armour in the background, between the bookshelves. And that's a skeleton on the left. Just a skeleton, not a Death. You can tell because it isn't wearing a cape.