Well, we are detectives. As much as it is to our disadvantage, it'd also be terrible form for them to not pick up on such details.

At the same time, however, your circumstances are also too far-fetched even for the chaos we encounter on a day-to-day basis. One mention won't hurt if we keep the details vague - a normal boy in England, for example, would have grown up hearing tales of knights and knaves and chivalry, and the era is covered in history class. It's only natural for them to look up how people actually lived in those times.

[In other words, as long as they stuck to known information about knights and talked about it as historical fact, it shouldn't be a problem.]

For our ease of mind, however - are there other topics you're comfortable talking about? Leading the discussion elsewhere is a viable tactic.