In one, governors are commended for their work in turning around the school's financial position and for their efforts to push up standards, while in the other report, the governors are criticised for their inexperience and failure to monitor progress.

Yet the two governing bodies are one and the same.

The governors of Dogsthorpe Junior School in Peterborough, praised by one team of Ofsted inspectors, are also responsible for Dogsthorpe Infants - on the same site - which fared less well under the scrutiny of another team of inspectors.

Ofsted admits its inspectors may have made a mistake

Nigel de Gruchy, general secretary of the National Association of Schoolmasters and Women Teachers, said the case underlined the need for an "inspector of inspectors".

"Inconsistencies in reports between Ofsted inspectors is not a new problem, but this is a spectacular example," he said.

A spokesman for the National Union of Teachers, John Perry, said he wanted an audit of Ofsted to make sure all inspectors were working to the same set of rules.

"There needs to be monitoring of the Ofsted system to make sure that inspection teams are all approaching schools in the same way, with the same parameters," he said.

The chairman of Peterborough's education committee, Harmesh Lakhanpaul, said he was amazed at the differences between the two reports.

"Ofsted may have very good reasons for coming to these conclusions, but it is baffling," he said.

Accuracy

A spokesman for Ofsted admitted it was possible that the inspectors had made a mistake.

"We have never said that the inspections are 100 per cent right or that the inspectors are always spot on, but the majority of inspections are accurate and schools are happy with the fairness of the comments that are made," he said.

"The inspection teams would have worked to the same Ofsted framework, which gives very clear and well constructed guidance about how teams should gather evidence.

"In this case, it could be that the governors do play different roles in the two schools and that they are more effective in one than the other. But the inspectors would not have made any snap judgements."