Been dead for a week. Now this post can finally die.
ohhhh...
nice grades
The grade boundries are Generally
A* 90% A 80% B 70% C 60% D 50% E 40% F 30% G 20%
But at his level (GCSE) I'm guessing he took all the Higher tier exams which means the Lowest actual grade you can get is usually a C and after that it is a Fail.