Sir Kevan Collins says he is concerned that the "educational legacy of Covid could be growing inequality". For independent school pupils in England, 70% of A-level results were A* or A, compared with 39% for comprehensive pupils. A-level results showed record levels of top grades.
The former schools catch-up tsar says he is worried about the gap in A-level results between state and private school pupils.
Sir Kevan Collins says he is concerned that the "educational legacy of Covid could be growing inequality".
For independent school pupils in England, 70% of A-level results were A* or A, compared with 39% for comprehensive pupils.
A-level results on Tuesday showed record levels of top grades.
Sir Kevan, speaking on the BBC Radio 4's Today programme, warned of a "huge risk" of widening social gaps in education in the aftermath of the pandemic.
"This is a deep problem in our system and one that seems to be growing," said Sir Kevan, who resigned in June over a lack of funding for his school recovery proposals.
Independent schools, which account for about 16% of A-level students, got higher results before the pandemic - but the gap has widened.
According to Ofqual figures, in 2019 there was a 24 percentage point gap between independent schools and comprehensives in A* and A grades at A-level - this year it has risen to 31 percentage points.
The Independent Schools Council, said this year's grading system had been a level playing field and that "irrespective of type of school" there had to be evidence of the quality of students' work.
The gaps were not just between state and private pupils, said Sir Kevan, but also in different parts of the country, warning that parts of the north of England were falling behind. In London almost 48% of results were A* and A grades, compared with 39% in the North East.
"We should be thinking about the inequality throughout the system," he said.
How schools were helped to recover after the pandemic would "determine the fate of the English education system" for the next decade, said Sir Kevan.
"We've got to get that right," he said.
In the wake of this week's record high grades in A-levels, with almost 45% of results at A* or A, there have been suggestions of changing the grading system, such as adopting the 9 to 1 system used in GCSEs.
But head teachers have said that any short-term change to a numeric system was "unrealistic" - and it is not expected to be part of plans for next year's exams.
Paul Whiteman of the National Association of Head Teachers said it took four years to plan the switch to using number grades for GCSEs.
Any such major change would require "meaningful consultation to ensure the fairest system for students," he said.
Geoff Barton, leader of the ASCL head teachers' union, said "rather than tinkering with different grading systems, the government should be concentrating on providing appropriate support for education recovery".
Exams are already going to be adapted next summer, to take account of lost time in school, but Mr Barton warned it would be "very harsh" on next year's exam candidates to have grades returned straight down to the pre-pandemic levels of 2019.
Mr Barton suggested there would need to be a "staged readjustment" from next year.
Labour's shadow education secretary Kate Green said the gap between results in state and private schools showed the lack of consistency in how grades were decided.
"The government didn't set down a clear standardised process early on last year - and schools were really awarding grades in very different ways," she said.
"There has been an increase in top grades for students from all backgrounds, and the relative increase of the proportion of As and above on last year is no higher in independent schools than in academies," said a Department for Education spokeswoman.
"We are committed to supporting students from all backgrounds. Ofqual report that the assessment approach this year is likely to have helped prevent previous gaps from widening as much as they would have done without this year's grading process."