To their advocates, modular exams are a valuable way of motivating underperforming pupils by breaking testing down into "bite-sized chunks". For their critics, however, including education secretary Michael Gove, they lack rigour and encourage a "culture of resits".
When Mr Gove announced that he would phase out modular GCSE exam courses in England from September 2012, the devolved governments in Wales and Northern Ireland faced a dilemma: whether to follow suit or stick with their current set-up.
While the respective administrations have forged their own distinct educational agendas in recent years, the GCSE remains the standard end-of-secondary-school assessment and performance benchmark across all three countries.
But now there are fears that Mr Gove's decision could lead to a detrimental fragmentation of the qualification across the UK.
Last week, Northern Ireland's Sinn Fein education minister John O'Dowd announced that he would not follow England's lead in stopping modular GCSEs, but instead would let schools decide what was best for their pupils.
He said that Mr Gove's decision "did not appear to have been taken on the basis of clear evidence or educational justification". "We looked at what was happening in England and took the views of stakeholders here into account before deciding on the best way forward," he said.
"The standard of GCSEs here and in England is exactly the same and it is vitally important that we ensure this continues to be the case and that learners can avail themselves of higher education and employment opportunities across these islands."
In Wales, the Welsh government is considering the future of GCSEs as part of a wide-ranging review of 14-19 qualifications, and has pledged that no changes will be made until at least 2014. Ministers are keen to stick with the modular system in the intervening period. A spokesman for the Welsh government said it was committed to not making significant changes to GCSEs until after the review "unless urgent action is fully justified".
And Cardiff-based exam board WJEC, which provides GCSEs in all three countries, said it had no problem with the continued availability of both approaches.
Critics say that the changes in England are being pushed through for political, not educational reasons. Brian Lightman, general secretary of the Association of School and College Leaders, said: "I welcome the decision in Northern Ireland and hope Wales makes the same sort of decision. The move in England does nothing to raise standards and it does not help learners.
"It is a shame the GCSE is becoming fragmented in this way, because it is easier for the users of those qualifications if they are of a set standard across the three countries."
But there are concerns that the Welsh government's hand could be forced by circumstances outside its control. Exam board OCR recently announced that it will no longer offer modular GCSEs in Wales, and would introduce linear-only exams from September, in line with developments in England.
In a letter to the Welsh government, it said: "Such arrangements present technical challenges relating to maintaining standards and it makes the shared task of maintaining confidence in GCSEs more challenging as some pupils will be seen to be getting more resit opportunities than others."
A spokesman for the Department for Education said it was up to Wales and Northern Ireland to decide how to run their education systems. "We make no apology for breaking the constant treadmill of exams and retakes throughout students' GCSE courses - school shouldn't be a dreary trudge from one test to the next," he added.
GCSE entrants gaining A*-C grades, 2011
Northern Ireland 74.8%
Entrants gaining five or more A*-C grades including English and maths, 2011
Northern Ireland 60%