King Charles III, 76, was, in the words of one royal insider, "well on his way to only being remembered as the man who cheated on Princess Diana." With his marriage to Queen Camilla nearing the 20-year mark,

"It must be tough for Charles, a man who waited over 70 years for the big gig, to play second fiddle to his son," Dunlop told the publication. The historian pointed out that "time and again recently, William has grabbed the headlines" rather than his father.

King Charles, Prince William, and Princess Kate might be in the same family, but the king sees his successors as rivals for his popularity with the public.

King Charles and Prince William are without doubt the spine upon which the current Royal Family rests. In time, William will take the throne after his father, and though it could be many, many years

The monarch, 76, has been married to Queen Camilla since 2005 -- but their relationship timeline wasn't all that straightforward.