@comeonnow I believe she chose to say war prisoner any other thing would've blown up her cover. Assuming you're right, the prince would've eventually found out the maids talking about how marie is a commoner. And calling herself a commoner is the worst thing she can do now because commoners don't have rules, grace, manners, or whatever small things that nobles had.
@icarushector and someunregpunk Also, even though they may not know her portrait, they know she's a young girl of noble birth fleeing. If they find a young girl with with immaculate hands worker as a waiter, they'll know she hasn't been working there for life. If they find a town where a girl moved into recently and the time frame matches, they'll likely find her suspicious. Now it's just a matter of asking them where they are from and if they are found to be from a fallen noble then they can just cross check them. This method is certainly not easy nor efficient, but it's still a viable method.