First, a circus moves around, but in a relatively short area. So the above study is relevant, but will nevertheless will need to allow for certain amount of variation.
Second, the box may have been the same as the hunters used to capture him. Someone should check that (I can do that, but not until the weekend). This is important because if MitD was sold with box, the wood origin is now completely random, based on the hunters point of origin (they'd carry the boxes with them). Since they are vaguely British, it would support oak, for what is worth.