Sex offenders in our schools. Just how many are there?

Bournemouth council has admitted that William Gibson, who has child sex convictions, was given a job at a local school. The Secretary of State for Education has been the target of an onslaught of criticism because a man cautioned for viewing child porn was cleared by one of her ministers to work as a PE teacher.

There was a huge outcry from parents, police and child protection groups after the revelation that Paul Reeve was cleared to work by Kim Howells, then a junior minister in the department, and now at the Foreign Office.

Conservative and Liberal Democrat spokesmen have stepped up the pressure on Ms Kelly, claiming parents had lost confidence in her management.

Gordon Brown, the Chancellor, said on Sky News: "I think Ruth Kelly will be the first to say this must be cleared up very quickly, and we must tell the public the full facts.

"Every parent will be rightly concerned, but I think we should wait until we see all the facts. These will be presented to the House of Commons and the public. People will then be able to make a full judgement on this, and that will happen as soon as possible. It is pretty clear we need to legislate changes and that is what we plan to do."

Two further sex offending teachers have been uncovered and the embattled Ms Kelly faces the prospect of more being found. Downing Street continues to insist the total of teachers with links to child sex would be a "small number" but the uncertainty did little to counter an impression that child protection registers were in a mess.

Anyone convicted of a sex offence is placed on the sex offender register which is maintained by the police. The Department for Education also keeps a blacklist of people banned from working with children which covers sexual offences as well as crimes of dishonesty and violence.

This List 99 does not automatically include people who have had a police caution for sex offences. Reeve was among 7,000 people whose names were given to police in Operation Ore, the far-ranging investigation of people who have paid to download abusive images of children from a US website. But he was only cautioned by police so was not automatically banned from working as a teacher.

Child protection charities and experts on sex offenders warned there may be others like him who had slipped through the net or who had viewed child porn but not even been picked up because of a lack of police resources.

The NSPCC said they were concerned police had been hampered because child protection was not a national priority. "We believe [most] people downloading child pornography are never caught and therefore never go on the sex offender register and do not receive help or treatment," Phillip Noyes, from the NSPCC said. "Sex offenders often store thousands of images and the information is often encrypted and difficult to decipher."

Derek Green, from the organisation RWA which rehabilitates sex offenders, said an independent body should take decisions on the employment of sex offenders, not ministers. He said: "The Government has not taken this issue seriously from the beginning. Mrs Kelly said evidence against Paul Reeve was inconclusive but which part of 'I did it' is inconclusive?"

David Willetts, the shadow education secretary, said that Sir Michael Bichard had recommended tightening the vetting procedures for would-be teachers in his report on the Soham murders as long ago as 2004.

Despite an assurance from then Education Secretary, David Blunkett, that the Government would consider the recommendations with urgency, "18 months on, nothing has happened", he said.

Mr Willetts told BBC Radio 4's Today programme: "One of the things I find most worrying, and I think the reason why there is this loss of confidence in the department and in Ruth Kelly, is that these cases have been going on even since the Soham murders and even since the Bichard inquiry."

The Liberal Democrat education spokesman, Edward Davey, said: "Urgent priority must now be given to restore confidence of parents, teachers and the wider community. This Government has got its information system in such a mess that child protection is being undermined. This is a failure of the highest order."

HOW A CHILD PORN OFFENDER WAS ALLOWED TO TEACH

Although the Norfolk teacher Paul Reeve had been placed on the national sex offenders' register, he was not put on the Department for Education and Skills' (DfES) List 99.

Reeve was arrested in April 2003 during Operation Ore and cautioned for "inciting to access child pornography". The anomaly arose because Reeve was cautioned, but not convicted. Only sentenced offenders go on List 99 automatically, banned for life from working in schools.

Ministers decide case by case if someone who has been cautioned should teach in schools.

Kim Howells, then a junior minister at the DfES, decided not to bar Reeve.

He was allowed to teach at a Norwich school for just eight days,until police raised their concerns with the headteacher.

Ms Kelly has now suggested that people cautioned for sex offences are unable to work in schools in the same way as those who are convicted. The row has revealed that there are seven different sources of information on sex offenders.

Ms Kelly has told MPs she will streamline the number of lists of sex offenders and give police a greater say over who goes on List 99.

Steve Bloomfield