It's been a very long time since we have had a coronation in England, and people have forgotten just how odd the coronation service is.
Much of the language comes straight from the Old Testament with copious references to Israel and Jerusalem. For example the divine right of kings is asserted with the words "Zadok the priest and Nathan the prophet annointed Soloman king" and the English monarch is presented as the successor of Solomon and David.
Just about no-one believes in divine right now, including our Queen. But there are some real oddities in our system which harp back to a set of discredited, not believed, but not wholly disbelieved tenets. One of these is that the king of England is part of a line that goes back to Solomon (there are even genealogies that claim to show this) and therefore our royals undergo the Jewish ritual of circumcision.
And yes Diana dug her heels in and said no.
By the way there has recently been a dna test released which shows Harry is Charles' s son.