I'd like to look at this issue logically. This result is a norm referenced result, not a criterion referenced one. It is based on comparing each result with all the others in this year's cohort. It does not show that the pupils are competent or otherwise, merely that some are more competent than others. In no way can it reflect on the quality of teaching. To do that it would need to measure performance in some direct way, say by stating x% could correctly point to the CPU when required.
If, as has been suggested, the examining body is using percentiles, then they have decided that only 40% will be awrded a grade B. Otherwise, it is possible that the results show a significant, but relatively small number of candidates acheiving very high marks, pushing the marking system out of line. This is entirely possible with IT, as some will have been trying to hack the school servers for a year or two, but without knowing how the thresholds are determined, it is impossible to say wether this would explain the anomaly.
Biting the hand that feeds IT
