I’m not aware that Prince William ever made any public statement about his education. However, with a good reference from Eton (which I’m sure he got) his grades were within the usual range for the University of St Andrews, but not Cambridge University. What happened in the sixties with his father is not relevant. It was not the sixties when he applied, things had changed, and there may have been public protests at any favoritism. It is not true that Royals or Aristocrats now enter Oxford or Cambridge unless they have the usual top grades required for entry. They are public universities and it would be too controversial.