The dust has settled on the drama of the court case, lessons have been learned and new safeguards put in place by exams regulator Ofqual.

So it stands to reason that this August should see no repeat of last summer’s GCSE English grading controversy?

Wrong, say heads’ leaders. And they have told TES they are also anticipating further rows blowing up over GCSE results in maths and science.

More than 30,000 pupils unfairly missed out on crucial C grades in 2012 according to schools, unions and local authorities, who took the fight to get them changed all the way to the High Court. There they argued unsuccessfully that a dramatic increase in grade boundaries between January and June last year was a “statistical fix” that amounted to an “unfair” and “capricious” “abuse of power” by Ofqual and two exam boards.

There can be no such dramatic increase in boundaries this year, because there will not be any grades awarded until all modules assessed in January and June 2013 have been marked.   

But the Association of School and College Leaders (ASCL) doubts whether that will be enough to avoid further trouble.

“There will be some significant turbulence again this year,” Malcolm Trobe, the association’s deputy general secretary, warned, “We are pretty certain that will happen because those schools who went down last [in terms of GCSE English grades] could go up and vice versa.”

The heads’ case is simple. They point to the increased emphasis placed on ensuring “comparable outcomes” by Ofqual, which last year ended GCSE grade inflation for the first time in the qualification’s history. The heads say this has made grading a “zero sum game”.

Mr Trobe believes schools that were caught out last year with large drops in the proportion of pupils getting good English grades - down by as much as 15 percentage points  - will have raised their game to prevent the same thing happening in 2013.

But ASCL argues that with overall grade increases effectively capped - a point that Ofqual disputes - that will mean that other schools’ results will fall as a consequence.

The association is also concerned about the impact on grades of new science GCSEs - which have been deliberately toughened up - and about maths, which Mr Trobe claims has ongoing issues that were overshadowed last year by the English controversy.

“Small reductions in grades are not a problem,” he said. “But they could be if the impact is not a flat adjustment across the board.”

Ofqual has written to schools warning that it expects the “more challenging” new science GCSEs to lead to a “small drop in achievements overall”.

The regulator has also said comparable outcomes should be used only when there has been “no substantial improvement in the quality of teaching and learning”.

So if teaching gets better then overall grades should be allowed to rise and there will be no zero sum game. Last year grades in 37 GCSEs did go above the comparable outcomes limits set by Ofqual.

Nevertheless it remains unclear exactly what needs to happen for the regulator to decide that teaching and learning has substantially improved.

So anyone expecting GCSE results day on 22 August to pass by without further recrimination may well be disappointed.