It was said by a very famous astrologer of the time (I think it was Noel Tynan, can't remember) who drew up a chart for Charles when he was born in 1948, and he said Charles will never be King. Several other astrologers agreed. I think Ive read that William has the important planets in Leo that is the 'sign' of monarchy, but I haven't read his chart for years. I think George also has.
I've heard the complete opposite. That The Queen, Charles, & Harry have the monarch signs and William will never be King with George possibly being/not being.