Boris Johnson got an angry response after telling school pupils that the exam results crisis was caused by a “mutant algorithm” and he was glad it had been “sorted out”. The National Education Union (NEU) called the prime minister “brazen” after he appeared to shrug off responsibility for the fiasco. Johnson was giving a speech to students on Wednesday at Castle Rock school in Coalville, Leicestershire. As well as welcoming them back to school and reassuring them it was safe, he said: “I’m afraid your grades were almost derailed by a mutant algorithm and I know how stressful that must’ve been for pupils up and down the country.” He added: “I’m very, very glad that it has finally been sorted out.” This month, Gavin Williamson, the education secretary, ditched the algorithm for moderating A-level and GCSE grades in England after a week-long outcry from pupils, parents and teachers. Days earlier, Johnson had said the results were “dependable” and “robust”. Even after the U-turn, Nick Gibb, the schools minister, said of the algorithm: “The model was a good model, and we continued to refine it.” Kevin Courtney, a joint general secretary of the NEU, criticised Johnson’s comments on Wednesday, saying: “It is brazen of the prime minister to idly shrug away a disaster that his own government created. “Parents, students, teachers and heads will be horrified to see the leader of this country treat his own exams fiasco like some minor passing fad. The public will not easily forget the emotional rollercoaster of this year’s results season. It is certain to put a long-lasting dent in the government’s reputation on education.” The shadow justice secretary, David Lammy, tweeted: “Boris Johnson just told schoolchildren their grades were ‘almost derailed by a mutant algorithm’. Could someone please gently remind him of the identity of the prime minister who is supposed to be in charge?” The algorithm was devised by the exams regulator Ofqual in accordance with Williamson’s instruction to avoid grade inflation after the coronavirus pandemic caused the closure of schools and the cancellation of exams. Ofqual’s chief executive, Sally Collier, resigned on Tuesday.