Well she didn't want to say it but Rarity's accent is that stereotypically upper class WASP accent which IS associated with New England generally. And in CT upper income bracket is more Fairfield (and some Litchfield) county then it is the rest of the state. NYC metro area and all. I just can speak to what portions of the other states in New England its associated with. Of course Bridgeport should more then cancel that out in a fair world.I once saw Gotham mapped to about there in Young Justice and did not disagree.
Really in all of New England (and NY because that erroneously gets lumped in too) people don't have accents. Well beyond "American" of course.