Charles is next in line by law.
Of course, if Charles dies before Elizabeth, that could change the line of sucession (to Andrew?).
No Andrew would not follow Charles if he were to croak. His Son William would follow, then William’s children then Andrews and his girls in the order of their birth....Poor Princess Royal is beneath her brothers as of now.
No, the eldest son of the eldest son inherits, not the brother of the eldest son. If Charles died before Elizabeth, then William is the heir. If Charles and William were killed in the same car accident, then Prince Harry would be the next heir. If he died without issue, then Andrew becomes the heir, and then after him his eldest daughter, etc.
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Charles is next in line by law.
Of course, if Charles dies before Elizabeth, that could change the line of sucession (to Andrew?).