The new exams regulator failed to achieve consistent grading standards across GCSE science for the second year running, a report published today reveals.

Ofqual had to ask exam boards to tighten their standards for GCSE science this summer to avoid a repeat of last year’s controversy surrounding the qualification.

But despite this, the regulator has admitted there was still inconsistency between the three main English boards in 2009, mainly at grade C - “with OCR and Edexcel appearing more lenient than AQA”.

The report also implies that standards have been consistently lower than predecessor qualifications in previous years since 2008, when the new GCSE science specifications were first introduced.

That summer saw the regulator intervene to ask AQA to lower the mark needed to achieve a C in GCSE science. The board did so “under protest” and claimed that its grading had maintained standards with previous years, and that it was its rivals that had made the exam easier, an accusation they denied.

Now AQA’s position appears to have been vindicated. It has emerged that its 2008 grade C boundary remained more severe than the other boards, even after it was revised.

And when Ofqual asked boards to “tighten their standards” for 2009, it was the AQA standard from 2008 that they were expected to fall into line with.

But this week’s report shows there was still variation this year. Ofqual says this is partly because of the modular nature of the exams, which means units had already been completed before standards were tightened. “There is still work to be done to complete the work of bringing standards into line,” the regulator said. “It is Ofqual’s expectation that by summer 2010, the differences between awarding bodies will have been substantially reduced by tightening standards further, where that is fair and appropriate.”

But that will still be a stopgap solution. In March, Ofqual revealed its wider concerns about the reliability of GCSE science and the number of resits possible, and said it had ordered all boards to introduce replacement qualifications from 2011.

Mike Cresswell, AQA director general, said: “We are pleased to see Ofqual’s commitment to bringing the other awarding bodies into line with AQA’s standard in the future.”