It was an issue that the Bichard inquiry, launched in the wake of the Soham murders committed by school caretaker Ian Huntley, was supposed to lay to rest.
But the discovery of a PE teacher in Norwich who had been cleared to work in schools despite being cautioned for accessing child pornography on the internet reignited concern about the potential for abuse in education.
Over the next 10 days, a media frenzy uncovered about 10 more cases, including that of William Gibson, convicted of indecently assaulting a 15-year-old and found teaching at a boys' school in Bournemouth.
It later emerged, in Ruth Kelly's statement to the House of Commons as her political future hung in the balance, that 88 sex offenders had not been included on List 99 and so banned from working with children.
Of these, 56 had been cleared by ministers, while it is believed that the remaining 32 were never referred to the Department for Education and Skills for inclusion on the list.
But Ms Kelly stemmed the tide of criticism with a package of reforms which included a blanket ban on sex offenders working in schools or colleges.
She also announced that ministers would no longer decide who would be banned from working with children, with the decisions to be taken by an independent panel instead.