British Prime Minister Boris Johnson's government was facing a backlash over pupil's grades on Friday after administrators cut the marks of two out of five children who went through England's benchmark school leaving exam. Opposition leader Keir Starmer led a charge against the government's handling of the awards following the pandemic and a decision not to hold final examinations. "Across the last 24 hours we have heard heartbreaking stories and the scale of the injustice caused by the fatally flawed results system has become clear," he wrote on Twitter. "Young people and parents right across the country, in every town and city, feel let down and betrayed." The plight of two pupils among hundreds relayed on radio and television was emblematic. Mithusan Thiagarajah was offered a place to study medicine at Cambridge University but the offer was withdrawn when the predicted 4A* result was downgraded. "No one has ever gone to Cambridge in my school," he told the BBC. "I wanted to make everyone who believed in me proud, my parents, my school and most importantly myself. I knew I would get those grades if I actually did those exams." Another pupil reacted to the award of a D grade where her teacher had given a B. "I've never got a D in my life ever, I just don't want a D." Mr Johnson defended his government’s handling of the pandemic-hit school exam scores in England after swathes of pupils' grades were downgraded by an algorithm in what the opposition Labour Party described as a “fiasco.” With pupils unable to sit tests because of the coronavirus, teachers gave an estimate, which was then adjusted by exam boards. According to the Office of Qualifications and Examinations Regulation (Ofqual), 39 per cent were downgraded by the algorithm, which also took into account pupils' past test scores and - controversially - results achieved by past cohorts at their schools. “I think this is a robust system and one that is dependable for employers,” Mr Johnson said. “It’s very important that for years to come people should be able to look at these grades and think these are robust.” The backlash over exam results adds to the criticism facing Mr Johnson over his handling of the pandemic and on education, with ministers under fire over plans to get schools reopened full-time in September. That’s critical to the government’s broader plans for reopening the economy, because keeping pupils at home makes it more difficult for parents to go to work. Mr Johnson also defended Education Secretary Gavin Williamson over the exam furore, saying, “It was obviously going to be very difficult in the absence of formal proper exams.” The Conservative Home website, a party aligned forum, applauded Mr Williamson for fighting a battle against grade inflation (most teachers are optimistic about the work of their pupils) but cautioned he was not well placed for the intensity of the oncoming storm. Commentator Henry Hill compared the grades controversy to picking a winners for this summer's postponed Olympic Games. "Trying to hand out grades based on cancelled exams is like trying to issue medals for a cancelled Olympics. No matter how clever the maths is, people are going to be unhappy. "Few people, if any, seem to have grasped in advance the scale of the problem. "When the dust finally settles, this will join the flailing effort to get schools open on the long, long list of failures of the state to be picked over post-pandemic." Mr Williamson has said students unhappy with their grades would be able to appeal, and would also be able to choose the highest score from either their calculated grade, the result of an exam sat later in the year, or the result of a “mock” or practice exam taken before the pandemic at the start of the year. The plan, announced just hours before the results were released, was criticised by Labour and teaching unions. They said “mock” exams were poor indicators for likely performance in final tests, and that it would be unfair to make students sit exams many months into the the future. Ofqual said grades were downgraded because the estimates provided by teachers had been too optimistic, and would have led to unprecedented grade inflation had they stood. A-Levels are also administered for UAE students but under a different standalone testing system.