The rise in grades likely in this year's GCSEs and A-levels is not sustainable in the future and would erode confidence in the qualifications if it continued, a senior Ofqual figure has warned.
Ian Bauckham said that teachers using evidence and professional judgement were still likely to award grades above that which every student would achieve if exams had been held.
The exam regulator's interim chair told the Association of School and College Leaders' conference today that this will mean an increase in overall grades, which will need to be controlled again in future.
"If repeated year on year, it would, of course, cumulatively erode the value of the qualification, so it will need to be controlled," Mr Bauckham said.
GCSEs 2021: No 'Weimar' grade inflation, says Ofqual chief
Exclusive: GCSEs 2021 ‘Weimar’ grade inflation warning
Boris Johnson: GCSE and A-level 2021 exams won't happen 'as normal'
He added that this did not make this year's qualifications less valuable, but said it was not sustainable in the long term.
His message contrasted in tone with the more reassuring line being given at the same time by Ofqual chief regulator Simon Lebus.
Speaking during a parallel online seminar run by the NAHT school leaders' union this afternoon, Mr Lebus said teacher judgements would mean "some small upward pressure on outcomes, not the Weimar-style inflation or prizes for all that some commentators have unhelpfully suggested".
GCSEs and A levels 2021: Teacher assessment 'will deliver higher grades'
Mr Bauckham explained how he expected that teachers providing grades would lead to higher results, even though they are acting in good faith.
He said: "Imagine I am a self-disciplined teacher determined to act with integrity when grading my students.
"In 2021 I have a class of 30 Year 11 GCSE candidates and five of those candidates have produced work on more than one occasion and, under reasonably controlled circumstances, that leads me to believe they are capable of getting a grade 9 on the day of the exam.
"In reality, I know that all five probably won't quite manage it on the day, despite the evidence. The problem for me is I can't be sure which of the five will and which of the five won't.
"So acting with complete professional integrity and using the knowledge I have of normal grading standards... following exam board guidance, I decided to submit a grade 9 for all of them.
"That small act of professional judgement, made in perfectly good conscience, with good evidence available for scrutiny if requested, will inevitably have an impact when it's repeated across the system."
He added: "Does that render this year's qualification less valuable? No, I don't believe it does."
However, he added: "Would this be sustainable if it was repeated year on year? No, it wouldn't because over time, if repeated year on year, it would, of course, cumulatively erode the value of the qualification, so it will need to be controlled.
"But to do so we need to be at the point where we can again offer fully regulated national examinations, and this year we quite simply cannot."