Many will be hoping Gavin Williamson will be able to provide some sort of fair solution to this year’s A-level and GCSE mess when he stands up in Parliament today.

But, as the education secretary must already fully appreciate, there are no easy answers. Last year’s GCSE and A-level results season was, frankly, a disaster. And there are several reasons why this year’s will be even harder to solve:

Boris Johnson: Prime minister reveals exams will not happen ‘as normal’ this year

Heads: DfE criticised for ‘deafening silence’ on closing Covid exam learning gap

GCSEs 2021: Covid impact may be flagged next to grades

Why GCSE and A-level grades won’t be fair this year

1.  We already know that the most obvious solution doesn’t work

Exams cancelled, most coursework done away with - how do you dish out GCSE and A-level grades? The obvious answer was attempted last year when our first lockdown came in.

You get teachers to calculate the grades they think their students deserve. You get schools to confirm them and work out rank orders for each subject in schools in case the grades themselves need to be adjusted.

And then you get Ofqual to moderate the results with a statistical model using the previous year’s grade distributions at national and school levels - an “algorithm”, if you will.  

It never felt perfect last year, but it seemed the best of a bad set of options until, of course, students and schools received their final “results”.

It’s one thing to get a hugely disappointing grade when you’ve actually sat an exam. But it’s quite another when that grade has been set by an algorithm and you have had absolutely no agency in a process that will play a big part in determining your life chances.

With hindsight, the resulting uproar feels inevitable. The forced U-turn resulted in a grades bonanza, at national level at least, but absolutely no standardisation. Which brings us on to the next problem.

2. How on earth do you set standards that are fair?

Mr Williamson is already committed to this year’s cohort receiving much more generous grades than a normal year, in line with those issued following last summer’s U-turn. But that throws up two very tricky problems.

The first is easy to understand but impossible to solve. Exams grades are supposed to be a reliable measure of attainment that allow employers and education institutions to compare candidates across different years.

But the 2020 mess means that this key attribute has been lost - for that cohort at least. And Mr Williamson’s generosity commitment for 2021 will only compound the problem.

Previous pre-pandemic cohorts now have unfairness baked into the system - their GCSE and A-level grades were issued on a much less generous basis than those of 2020 and 2021.

The second problem is also very difficult - if not impossible - to solve, and extremely complicated. It stems from the fact that last year’s teacher grades were allowed to stand without any moderation.

That means that it is also almost inevitable that there will be unfairness within the cohort because grades will have been issued by teachers and schools who have not taken a uniform approach.

We definitely know that last year’s grades were not, as a whole, in line with exam standards from previous years, because, overall, they were so much higher.

But it is highly unlikely that teachers and schools will have taken a uniform approach in pushing them up. Teachers are human beings, after all - so while some may have taken a very cautious, by the book, approach to grading, others will have been more generous. Perhaps they did that safe in the knowledge that moderation would sort things out anyway, but, of course, in the end, that moderation never happened.

So what do the exam authorities do now when they want to look for reliable benchmarks on where to set grades for 2021? The truth is there aren’t any - the standards within their benchmark year, 2020, are likely to be all over the place.

It would perhaps be possible - but complicated - to work out which schools were particularly generous last year and then take that into account when setting standards for this year’s grades.    

But that would mean students in some schools receiving grades that were dramatically lower than their counterparts the previous year despite having suffered even more Covid disruption. Which minister or exams chief would be brave or foolhardy enough to attempt that solution?

3. We appear to have ruled out our best option of giving students some agency

Wales has taken an approach that avoids the need for exams, but involves students’ actual work being externally assessed. So the grades are based on something the students have actually done, and the vagaries of unmoderated and, therefore, inevitably unfair teacher assessment, and the risk of exam cancellation, are all avoided.

England chose not to go down this route, clinging on - until Monday evening - to the notion that the GCSE and A-level exams could go ahead.

Why was this decision taken? Perhaps because the changes to GCSEs and A levels made under Michael Gove pretty much dismantled the previous coursework system.

If it turns out that a Welsh-style solution is possible, then the question has to be asked - why weren’t we doing this in the first place?

4. We still have no solution to the biggest unfairness of all - differing degrees of Covid disruption

This was the biggest problem that Mr Williamson faced when he unveiled his last set of solutions to the 2021 exams conundrum. But it was one that he chose to kick down the road by hiving it off to an expert group that he promised at the start of December.

Since then, however, we have heard nothing - we don’t even know if the expert group exists yet. But this week’s cancellation of GCSE and A-level exams has not made this key problem go away - students in different parts of the country have still been through widely differing levels of Covid disruption.

If anything, the problem has suddenly become much much worse. The prolonged period of remote learning students now face will introduce dramatic new inequities within the GCSE and A-level cohorts thanks to the digital divide and widely differing home circumstances.