Keir Starmer today joined the A-Level backlash demanding standardisation is ditched in favour of teachers' suggestions - despite regulator Ofqual warning those grades were 'implausibly high'.
The government is facing a storm after nearly 40 per cent of results were downgraded by the computer model deployed when exams had to be cancelled due to the coronavirus crisis.
Boris Johnson and Education Secretary Gavin Williamson have defended the outcome as 'robust' and 'credible', while Ofqual pointed out that there would have been massive grade inflation if moderation had not been used.
But Sir Keir today turned up the heat by calling for England to follow Scotland's example by scrapping the standardisation altogether, and relying on estimates from teachers.
'The unprecedented and chaotic circumstances created by the UK Government's mishandling of education during recent months mean that a return to teacher assessments is now the best option available,' the Labour leader said.
'No young person should be at a detriment due to Government incompetence.
'Time is running out. We need action in days, not weeks.'
When the huge U-turn was made on a similar computer model in Scotland, the Higher pass rate soared by 14 percentage points from last year.
Sir Keir Starmer ([pictured on a visit to Darlington yesterday) has urged the government to emulate the U-turn on A-Level grading in Scotland
Education Secretary Gavin Williamson had faced pressure to address the 'huge injustice' of the 2020 results by head teachers and the Labour Party
Data revealed that the marks of poorer pupils in England were more likely to be downgraded by the algorithm
Ofqual had estimated the A-Level pass rate would be 12 points higher if teacher assessments alone were used.
And a spokesman told the Telegraph today that the 'standard applied by different schools and colleges varies greatly'.
'A rare few centres put in implausibly high judgments, including one which submitted all A* and A grades for students in two subjects, where previously there had been normal distribution,' the spokesman said.
After the 2020 exams were cancelled due to coronavirus, this year's grades were been calculated by a statistical model that considers the pupils' past performance along with the historic grades of their school, along with a rank order drawn up by teachers.
But results day has seen growing complaints by pupils and schools about the statistical mechanism used to award grades - which, it is claimed, has unfairly punished some.
Several pupils at one sixth form college were downgraded after getting top predicted grades.
Wiktoria Sniadowska said she would 'definitely' appeal after a computer algorithm cut her straight As to BBC. She is continuing her studies at Leyton Sixth Form College in London, where she will take an art foundation diploma.
But she said: 'I know that if I'd done my exams, I'd have got better grades. It's unfair.'
Tamzin Iyayi lost out on a place at Cambridge after being marked down from A*AA in history, law and politics. She said: 'I just feel let down by the Government.'
Aqsa Ali had been offered places to study politics and international relations. But she missed out after being downgraded to a B in politics and Cs in history and religious studies.
Students burn their A-Level results at the London Dungeon as students find out whether they have got a university place
Left to right: Victoria Sniadowska, Tamzin Iyayi and Aqsa Ali. Wiktoria Sniadowska said she would 'definitely' appeal after a computer algorithm cut her straight As to BBC
Maks Ovnik cares for his grandmother, 102, alongside his mother on the Isle of Wight
She said: 'It's had a big impact on my mental health and confidence.'
Elsewhere, a young carer had his A levels lowered by as much as three grades, putting his university plans in doubt.
No apology from Boris Johnson as he insists results are 'robust'
Boris Johnson has insisted that the exam results published today are 'robust' and 'dependable'.
The Prime Minister said: 'Well let me first of all say that I want to congratulate all the students who have worked so hard to get the grades that they have and have done so well.
'And let's be in no doubt about it, the exam results that we've got today are robust, they're good, they're dependable for employers, but already I think that there's a record number of candidates, of students, who are able to get their first choice course at the university of their choice.
'Plus, there's a record number of students, of pupils, from disadvantaged backgrounds who now as a result of these grades, will be able to go to university.'
Mr Johnson also said that he has confidence in Education Secretary Gavin Williamson.
He said: 'I think obviously it was going to be very difficult in the absence of formal proper exams this year of the kind that we normally have because of the virus, we've had to put in the system we have.
'I do think it's robust and as I say, a couple of things I think are very important - first of all, more students than ever before are able to go to their university of choice, to do the course of their choice.
'And on your point about kids, pupils from disadvantaged backgrounds, more than ever before are now able to go to university, are going to university this year as a result of the grades they've got today.'
Asked if he has confidence in Mr Williamson, he said: 'Of course I do, but I think this is a robust system and it's one that is dependable for employers.
'It's very important that for years to come people should be able to look at these grades and think these are robust, these are dependable.'
Maks Ovnik cares for his grandmother, 102, alongside his mother on the Isle of Wight. He got ABB in his mocks and his school gave him AAB in maths, computing and physics.
But these were downgraded by Ofqual to ADE, meaning he loses his place to study physics at Southampton.
Maks, 18, who plans to appeal, thinks his results were downgraded due to his school's performance last year. He said: 'It's not a nice feeling at all.'
Education Secretary Gavin Williamson had faced pressure to address the 'huge injustice' of the 2020 results by head teachers and the Labour Party after data revealed that the marks of poorer pupils in England were more likely to be downgraded by the algorithm.
Sources close to Mr Williamson say that there will be no U-turn, adding that the model used had been the fairest way to deal with the matter, given the circumstances.
They highlighted Ofqual figures that revealed nearly twice the number of pupils would be awarded A*s than in previous years if 'optimistic' grades were permitted to stand.
Mayor of London, Sadiq Khan, has written to Mr Williamson saying he is 'very concerned at the publication of, and issues surrounding, [this year's] A-level results'.
He said: 'The Government's last-minute decision to revise A-Level grading options is the latest in a series of bewildering exam announcements at a time when pupils need clarity and certainty.
'I am particularly concerned at disadvantaged pupils and those in state sixth-form and further education colleges losing out disproportionately.
'It is absolutely vital that ministers now provide clear information on the process for contesting grades to ensure every teenager receives a mark which reflects their effort and ability - both this week with A-levels and next week with GCSEs.
'I urge you, on behalf on London's next generation, to look at what Scotland has done, to admit that mistakes have been made, and to ensure that teachers' assessments are properly taken into account as these provide overall a far fairer way of attributing grades compared to what we have seen today.
'I would welcome your urgent response to this letter.'
One Government source said: 'There are always people who do not get their predicted grades. People seem to be operating with the notion that everyone should just get what their teachers think they should have got.'