From last week anyone convicted of a sex offence against a child is required to register with the local police, who will decide whether to alert headteachers.
Police forces have been given detailed guidelines on assessing the risk an offender poses to school children and the circumstances which justify revealing his or her identity. Now an interdepartmental group which includes education junior minister Estelle Morris is giving priority to the more tricky problem of telling heads what to do with the information.
The register, expected to contain the names of around 6,000 offenders, will be one of three separate sources of information on sex offenders for schools.
The criminal records agency, which will issue certificates to people who apply showing whether or not they have a clean record, is still to be set up.
Schools may be included in a restricted list of organisations who will be able to request information from the agency in order to vet applications for non-teaching posts.
For teacher applications, schools are expected to continue to rely on List 99, compiled by the Department for Education and Employment. The list currently names 2,058 people of whom 96 - 0.5 per cent - are women.
Teachers convicted of, or cautioned for, sex offences automatically go on the list.