This is one of multiple Jacks...most of them, unfortunately, give it a good try but just aren't close enough and to me, it seems odd. Animated characters you can get away with it easier, but when you have characters in a live action movie the actors must look, act, speak, etc exactly like the real thing or else something is lost. Besides, it's a big day at Hogwarts and at Hogsmede....Muggles are in for the first time...DD and other professors are needed in the castle to help with tours...make sure none of those muggles go poking about where they shouldn't be...and the students all have class and/or need to assist with tours.