The revelation that the exam regulator Ofqual, contrary to its previous insistences, ordered exam board Edexcel to alter its GCSE English grades boundaries just two weeks before results were published has intensified the controversy around the papers. Until now, Ofqual has maintained that exam boards set June's grade boundaries (which were harsher than those used in January) "using their best professional judgement". But, thanks to the leaked letters obtained by the Times Educational Supplement, we now know that it ordered at least one to adopt new boundaries in order to bring down the number of C grades awarded. Glenys Stacey, Ofqual's chief regulator, will answer questions from MPs on the education select committee at 9:30am this morning, with Michael Gove due to appear tomorrow.

And it's Gove that Labour is concentrating its fire on this morning, urging him to order an independent inquiry into the affair. The unspoken suspicion is that the Education Secretary leant on Ofqual to intervene. In a letter to Gove before the results were published, the regulator warned that a crackdown on "grade inflation" would make it "harder for any genuine increases in the performance of students to be fully reflected in the results."

Meanwhile, the decision of Welsh education minister Leighton Andrews to order Welsh pupils' papers to be regraded has made Gove's refusal to act all the more conspicuous. Gove has previously argued that the fiasco simply reinforces "the case for reform" - modules and units should be scrapped and GCSEs replaced with new O-level style exams. But that will be of little to comfort to those English pupils who saw their papers marked more harshly than those sat in January. Until the Education Secretary acts to correct this injustice, he will rightly be accused of complacency.