LONDON—A public inquiry into Britain’s contaminated blood scandal, which led to the deaths of more than 2,000 people in the 1970s and ’80s, began hearing evidence Monday from former students at a disabled children’s school where dozens died after being given blood products tainted with HIV and hepatitis. Former students and parents from Treloar’s College, an English boarding school, were testifying to the Infected Blood Inquiry because the school’s health center gave children infected blood products such as plasma to treat their haemophilia, a condition that impairs the body’s ability to make blood clots. Some 89 former students were infected with HIV or hepatitis as a result and less than a quarter of them are still alive. Gary Webster, one of several former students giving evidence this week, recalled the day the school informed him that he was infected. He was told “the outlook’s not good, we can’t guarantee you …