The scandal saw the Department for Education forced into a U-turn after its algorithm intended to prevent grade inflation saw 40% of predicted results downgraded, resulting in public outcry.
The algorithm was subsequently scrapped, with children being awarded the grades they had been predicted by their teachers when 2020 GCSE and A-level exams were scrapped.
Appearing at the UK Covid-19 Inquiry on Tuesday, former prime minister Mr Johnson acknowledged that the system had “failed” and the government had “got the wrong initial model”.
But he insisted that the “bad system” was “an accident” born of “exceptionally difficult circumstances” and had been based on “good intentions”.
Then-education secretary Sir Gavin Williamson faced strong pressure to resign over the fiasco, but held on for another year until he was dismissed in Mr Johnson’s 2021 reshuffle.
However, a message shown to the inquiry on Tuesday indicated Mr Johnson had considered sacking Sir Gavin in the summer of 2020.
In the message, sent from Mr Johnson to his chief adviser Dominic Cummings, the then-prime minister complained that his break in Scotland had been interrupted and said he was back at Chequers, his country retreat, “in a thoroughly homicidal mood”.
He said: “We need a plan for the dept of education. We need a perm sec and we need better ministers and quite frankly we need an agenda of reform. We can’t go on like this. I am thinking of going into number ten and firing people.”
Jonathan Slater, the then-permanent secretary at the Department for Education, was sacked over the exam results while Sir Gavin was not, leading trade unions to accuse Mr Johnson of treating him as a “scapegoat”.
Asked whether he should have sacked Sir Gavin, Mr Johnson told the Covid Inquiry: “I think if I look back at my handling of my beloved colleagues over the three-and-a-bit years I was in government, I can think of all sorts of changes I might have made.
“But I don’t think there’s any point in speculating about it now, except I think that on the whole, given the difficulties that we faced, I think that the department under Gavin did a pretty heroic job in trying to cope with Covid, and that was my judgment.”
Mr Johnson also accepted that the algorithm, which he described as “a disaster” had been deliberately designed to prioritise avoiding grade inflation over other considerations.
Asked by inquiry counsel Clair Dobbin KC whether he accepted this, he said: “Yes, As far as I understood, the anxiety was that there would be a year, an abnormal year, in which there was such grade inflation as to devalue everybody’s grades.”
