Bruce Roth, 46, a teacher at the £30,000-a-year Wellington College public school in Berkshire, was today found guilty of sexually abusing five young boys.
Roth, who taught maths at the school until he was arrested, groomed and performed sex acts on three boys at the boarding school and two at King's School in Rochester, Kent, where he taught previously.
Roth strenuously denied the 17 charges against him, accusing his victims of conspiring against him because they did not like him as a teacher and calling one of them "sinister".
He remained impassive in the dock, apart from occasionally shaking his head, as the jury of six men and six women at Reading Crown Court returned their guilty verdicts on all counts after just over 18 hours of deliberation.
A woman in the public gallery burst into tears as they were read out.
The trial heard that two complaints were made against Roth over claims that he sexually touched one boy and repeatedly abused another, both aged between eight and 10, while an assistant housemaster at King's School between 1987 and 1994.
But the accusations were dropped - the second time following an internal investigation. He left the school and went to Wellington, where he taught until 2010.
Wellington College counts broadcaster Peter Snow, comedian and impressionist Rory Bremner, pop star Will Young and journalist and author Sebastian Faulks among its alumni.