"Hex" is the Roman prefix meaning 6. Not just for the English. Just as "oct" means 8.
Don't understand the Henry VIII reference.
Incidentally, although there have indeed been VIII kings of England called Henry, not many people know that there were actually XI English kings named Edward. The one who abdicated, commonly known as Edward VIII, should have been called Edward XI. When the Normans invaded in 1066 they rewrote history in many ways, including disregarding all English kings since 802 (when England was united as a single country). They demonstrated the same arrogance as the Spanish did centuries later when they occupied much of the Americas, in disregarding any civilisation and society that had existed previously. So they pretended the first three Edwards had never existed, even though William's (the bastard, later King William I) tenuous (fraudulent) claim to the throne was based on the actions of Edward the Confessor (who was Edward III in real time).
History lesson over!