The Arch Duke Franz-Ferdinand and heir to the Austro-Hungarian Empire, had such a union and therefore, his children had NO claim, whatsoever, to the throne, if the monarchy had survived WW I!
Being an aristo, in any nation, but especially in the UK, in 2018,has absolutely NO bearing on being a "ROYAL"; not to mention some many centuries back, legit or wrong side of the sheets, a birth to some long ago ROYAL was! ERGO, NO aristo is a "ROYAL", but IS a "commoner"!
And the whole stupid "QUEEN CHARLOTTE WAS BIRACIAL" crap is not only specious CRAP, but patently ridiculous!
The press in Great Britain, during the time King George III was alive ( and afterwards too ), was as brutal, if not more so, than what we have in the USA today! Political cartoons were vicious; even MORE vicious than today's FAKE NEWS and tweets! And before you claim that this stuff only reached a few, please allow me to disabuse you of that idea. This crude and yes, vulgar stuff was EVERYWHERE and because they were cartoons, even the illiterate could understand what the pictures meant, even though they couldn't read the words.
Di and Kate were/are commoners and "IF" somehow related to the ROYAL family, many, many, many, many generations back ( and far removed from the House of Windsors !), it's so far back, as to be completely removed from "consanguinity", that a claim of "INBRED" is beyond laughable in the extreme!
And FYI...the late Queen Mother ( Elizabeth II's mother ) was also a "commoner", though an aristo!
Thanks for explaining all that, Camilla.
It seems you are back.