Not relevant. The party was in Florida where the age of consent is 18.
“The party was in Florida where the age of consent is 18.”
Well, then, he may have a spot of bother. They didn’t used to call him “Randy Andy” for nothing.
Someone, of course, has to be willing to actually make a case out of it, and proving it in court is the hard part. Not to mention the possibility (hard to find a quick answer on the net) that members of the Royal Family may have some kind of diplomatic/sovereign immunity.