Child molester was given teaching job at a fourth school

The row over sex offenders in schools erupted once more yesterday as it emerged that a convicted child molester had found work in a fourth school.

Pressure on the Secretary of State for Education, Ruth Kelly, grew after it was confirmed that William Gibson was working in a Bournemouth school despite having been removed from three posts in the North-east when his conviction came to light.

It was also revealed that she was warned last year about serious problems in the vetting of registered sex offenders in the teaching profession. The Chief Constable of Norfolk wrote to Ms Kelly on 12 December detailing concerns about Paul Reeve, who was cleared to work as a PE teacher despite admitting viewing child porn. But she only launched an "exhaustive review" of other registered sex offenders last week after the case became public.

The Education Secretary's problems were further compounded last night when it emerged that Gibson had been working full-time at Portchester School, a boys' school, since term began this month, with occasional days as a supply teacher in the autumn term last year.

Gibson is not on List 99 and doesn't feature on the sex offenders register because his 1980 conviction predates its establishment. But a supply agency in the North-east refused to employ him after checking his past with the Criminal Records Bureau, and he was removed from three posts in the area when his conviction became known.

Meanwhile, questions were asked about the effectiveness of the vetting system to keep paedophiles out of the classroom, after it emerged that men on the confidential List 99 had been given official permission to teach.

Ms Kelly told the House of Commons on Thursday that an entry on List 99 was an "absolute bar" to teaching in schools. But it was revealed that Keith Hudson, from Sussex, was given permission by then Secretary of State, Estelle Morris, in 2001 to teach in all-girl schools, despite a conviction for possessing indecent images of boys five years earlier.

The Care Standards Tribunal backed Ms Morris's decision after hearing medical evidence that while Hudson's feelings towards young boys were " homosexual, paedophilic and inappropriate", he had "no interest in girls". And a man identified only as H, who was placed on List 99 after being convicted of indecently assaulting a 12-year-old boy in 1976, was given clearance by the tribunal to teach children aged 14 or above as evidence suggested he was a risk only to "young boys who are pre-pubescent or pubescent".

Officials at the Department for Education and Skills trawling records back to the 1970s admitted that the figure of about 10 offenders currently teaching could be an "underestimate".