At that time there where two sets of exams taken at 16 O levels and CSE.
The O levels where for Kids in grammar and private schools and the CSE's where for the kids who went to secondary modern schools who left at 15/16.
As I was dyslexic I was put in the CSE stream though I did get a grade 1 in maths and computer studies which is the same as a pass at O level I didn't get to do A level computing.
What is CSE? Google seems to think it's Certificate of Secondary Education. So, middle school -> early high school equivalent?
Grade 1? A level? Leave where, the school?
(I'm in the US, so that's probably the disconnect)