Really? He’s a direct (though not strictly patrilinical) descendant of the 7th century House of Wessex. Hard to imagine a more authentic pedigree than that.
(Note: link I added only goes from Alfred the Great in 849 CE, but you can trace his lineage back to the 7th Century House of Wessex easily enough.)
And Mountbatten is an anglification of the likewise German Battenberg.
(not legal advice)
Under English-derived common law (not ever active in the Vatican, unfortunately), I believe that a person’s name is a matter of fact based on what name the person uses and is recognized by in the community. So, if your birth certificate says “William Norton Fitzgerald”, but you call yourself “Bob Fitzgerald”, your parents call you that, your wife calls you that, your kids call you that, and people in the neighborhood call you that, then you are, in the eyes of the law, Bob Fitzgerald. A legal name change through the courts basically forces those <your favorite disparaging term> at the DMV and the passport agency to recognize this.
(not legal advice)
If so, how does she enter countries like the US where she is not Sovereign? I wouldn’t be surprised if the US (or some other country) makes an exception to this, though.
Does Obama carry a US passport when he travels the world?
Presumably when the Queen travels outside of her “realms & territories” it’s always as an official State Visit, and the receiving government makes the necessary arrangements.
I think this is a matter of being an official state visit or a private journey. I’m fairly sure that the king of Sweden has a passport for non official travels. One other thing is that heads of state don’t need a work permit (at least this is the case in Sweden) although the visit is part of their job. When Bush the second visited an EU meeting in Sweden my sister-in-law signed permits for everybody in the entourage except him.