Two cheers for A levels. The first goes to students for what they have achieved; the second to teachers for trying in good faith to ensure that the exams match their students’ abilities. A third cheer would be for the system itself, but that system is flawed. The last two years of school are defined by a set of exams, themselves defined by a purpose that they no longer fully serve.

Almost uniquely, our national system is characterised by an extreme specialisation in the upper secondary phase, whereby most students narrow down to three or four subjects. Under the Govian reforms, this anomaly will be accentuated, with many schools moving from a four- to a three-subject model in Year 12.

The A-level reforms, radical-seeming in some ways, did not set out to address the real problem. Prospects for fundamental reform (of sixth form as an educational stage rather than a discrete set of exam-based qualifications) remain pinned between the immoveable object of GCSE and the irresistible force of HE.

Specialisation seems justified by the fact that students are expected to have mastered the full range of subjects by age 16. Gove’s reforms could entrench this further, given that the GCSE hurdle is intended to become higher, but no less wide. (The GCSE reforms never set out to ask the existential question: why do we have a battery of high-stakes tests when 16 is no longer the school leaving age?)

The narrow sixth-form focus has served the universities, because they operate a three-year degree course model. For this to work, universities need students to arrive already fairly advanced in their chosen study. A levels were introduced precisely for the purpose of qualifying school students for admission to undergraduate study. They were not intended to be a national school leaving exam; they were designed as an admission ticket to higher education. But for want of something better (or an alternative with parity of esteem), they have become the national school leaving qualification.

So, our sixth form curriculum model exists simply because it can (given the existence of GCSE) and because it works for higher education, not because it necessarily makes educational sense. The reduction of the sixth form curriculum to a narrow set of academic specialisms represents a form of educational mortmain.

Some will object that this is too pessimistic, and that we shouldn’t allow a set of exams, or the particular selection concerns of universities, to determine what is taught in schools. Excellent schools already offer enrichment programmes that go well beyond the core of A level subjects, and valiantly seek to provide a broad and balanced, as well as deep, education beyond sixteen.

But the vertiginously high-stakes nature of A levels casts a shadow over all such initiatives. As long as GCSE clings on, and as long as only three subject exam grades really count for university entrance, the non-exam curriculum will always be at a disadvantage, and students will be the poorer for it.

Dr Kevin Stannard is the director of innovation and learning at the Girls’ Day School Trust. He tweets as @KevinStannard1

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