A hypothesis from the book entitled: The Ambassador and the Pharaoh. The famous anamorphosis of the Ambassadors (that is the distorted skull) was later painted into the picture, and probably not Holbein’s work.
The floor of Westminster and floor of the Ambassadors are similar to each other, but they are not exactly the same. The main difference is the hexagram in the middle of Holbein’s picture. It's hard to imagine that Holbein precisely constructed the perspective view of a hexagram, and then he covered almost the full image with the distorted skull. Nota bene: he did not paint such kind of anamorphosis, not earlier, not later.