[The fact he's even being asked these sorts of questions are a clue. It would have proven to him that Jim is a Precursor, except... well, the guy just doesn't really seem like one]

1868. My sister and I were recently knighted by Queen Victoria. Then I came here, and... you're going to tell me you're from some time in the future, aren't you?

[He says it in such a dry tone that it's more are you fucking serious than nope this isn't real]