The GCSE was originally intended to be a unifier, abolishing the old, invidious division between O levels for the academically orientated, and CSE for the rest. It was designed as a general certificate of secondary education.
Assessments focused on what students knew, understood and could do. To achieve this, the grade set extended from A all the way to G – above which, no formal pass mark was set.
But very quickly, the C/D boundary became tectonically active as the fault-line between plates of success and of failure.
The qualification’s inclusiveness was based on criterion-referencing, whereby a student meeting standards pre-set as descriptors would be awarded the appropriate grade, independent of the performance of others in the cohort.
This, of course, contributed to grade inflation, because the system could not preclude the year-on-year operation of a ratchet at the margins, and because teachers and students simply got better at preparing for and taking the exams.
Some of this involved gaming the system, through judicious choice of subjects and exam boards, and resources focused on students at league-table sensitive grade boundaries.
But a lot of it was simply teachers and students conscientiously following the rules: if you set the goal posts in a particular place, don’t be surprised if the players focus on the space in between.
All criterion-referenced assessments (as opposed to those that allocate grades to pre-set proportions of the cohort) are subject to grade inflation, but it only creates a crisis if grade distributions are suborned to measure school and system performance.
In any case, the solution to grade inflation is not to introduce a new top grade, any more than the solution to monetary inflation is to print notes of a higher denomination.
Political decisions regarding grade boundaries in the "reformed" GCSEs might lead to the qualification losing its educational anchor.
Two students who would have achieved A* might now be sorted into two groups if one is awarded a 9 and the other an 8. This would be to no educational purpose if the error margin is greater than the number of marks separating the candidates.
The decision on whether the acceptable pass should be a 5 or a 4, and the possibility of it rising in the future, are not educational considerations. They are levers to be pulled in the pursuit of system control.
We need to return to the idea of GCSE being a general qualification indicating a student’s readiness to progress. Given that most students stay in full-time education post-GCSE, the timing is anachronistic, certainly, although it is reasonable to assess school-leavers at the terminal point.
But why is it necessary to slice the cohort into grade categories of graphene-like thinness?
Universities that have to make finely calibrated selection decisions have other measures available.
Employers seek reassurance about the achievement of knowledge, skills and competencies, but it is difficult to see how their need is met by making micro-scale distinctions between candidates. There are other, fairer, means of selecting between applicants with broadly similar academic profiles.
Dr Kevin Stannard is the director of innovation and learning at the Girls' Day School Trust. He tweets as @KevinStannard1
For more columns by Kevin, visit his back catalogue
Want to keep up with the latest education news and opinion? Follow Tes on Twitter and like Tes on Facebook