Britain’s Education minister, Ruth Kelly, is coming under more pressure after details of a second case of a sex offender being allowed to work in schools emerged. A 59 year old man, who was convicted of indecent assault on a child in 1980, had been working as a substitute teacher in schools in the north east of England. Kelly has faced calls to resign over an earlier case in which a former senior official in her department judged a teacher who had a police caution for downloading child pornography posed no risk.The official, who now works at the Foreign Office, said he had acted on the advice and evidence available to him. Paul Reeve, a phsyical education teacher went on to work at a secondary school in eastern England until he was interviewed by police. Kelly has said she will tighten child protection laws. The government has launched a review into cases where registered sex offenders have been allowed work with children. A government spokesman said there had been only been a small number of cases.