This article is from the The Young Ones FAQ, by Andrew Wong BritCom@audiophile.com with numerous contributions by others.
O-levels were the exams taken by 16 year olds before they left school. A C
grade was considered a pass. You needed 5 passes to be allowed to the next
stage of British education, which was usually A-levels. Generally, British
students take 3 A-levels, and the grades you eventually get determine
which university you get to. If you get AAA, you get to go to the great
universities of Oxford, Cambridge and Bradford :) If you get less than
that, you are more likely to head for the "red-brick" universities or the
polytechnics (vocational colleges)
O-levels were eliminated in 1987 in favour of GCSEs. Many older people
tend to complain that GCSEs are much easier than O-levels...