A respected former head of Ofsted has called for a public debate about the future of school inspection, warning that today’s regime is inconsistent and too dependent on data.

Sir Mike Tomlinson, appointed Birmingham education commissioner by ministers after the Trojan Horse scandal, told TES: “Inspection is so important to the profession, it is so important to young people, it is so important to the parents of those young people, that maybe after 20-odd years there is every reason to look at it and say, `Have we got it right?’ ”

His comments came during another week of high-profile criticism of Ofsted. Shadow education secretary Tristram Hunt told teachers that the watchdog was starting to “choke” the “joy, wonder and beauty” out of schooling, threatening to bury it under an “avalanche of bureaucracy”.

The Labour politician joined headteachers’ leaders and Conservative party sources in calling for “far-reaching reform” of the inspectorate.

Sir Mike said that although inspection was an essential part of school accountability, he was worried about how it currently operated. “Ofsted and the government have become too data-reliant,” he cautioned, adding that there was sometimes an assumption that “data in itself leads you to conclusions”.

“It doesn’t,” Sir Mike said. “All it does, when it’s used properly, is enable you to ask the right questions. And that isn’t done as often as it should be.”

Sir Mike also told TES there was “a need to readdress the whole question of consistency of judgement”. He admitted that Ofsted inspection ratings had been inconsistent when he was chief inspector between 2000 and 2002.

But since then inspection outcomes had become even more important, he said. “In the now hugely high-stakes situation many headteachers and schools find themselves in, I think consistency can be the difference between keeping your job and losing your job.”

In January, Ofsted’s national director for schools, Sean Harford, publicly acknowledged that some inspectors relied on a “narrow range of data” and were “guilty of using the published data as a safety net for not making fully rounded, professional judgements” (” `We’ve not done enough to ensure reliability’ ”, News, 9 January).

He also admitted that the watchdog was inconsistent and did not “directly [ensure] that different inspectors in the [same] school on the same day would give the same judgement”.

No going back

Asked what he thought about calls for the abolition of Ofsted, Sir Mike said it was the way that inspection was carried out rather than the institution that mattered.

“You have to have a body for inspection across the country,” he told TES. “You can reinvent it if you want. You can rename it if you want. The government can do anything it wants, but at the end of the day you will not get rid of accountability with inspection as part of that.”

Asked how greater consistency could be achieved, he said the decision to stop using inspectors supplied by outside contractors was a “positive step in the right direction”.

Sir Mike argued that the market for inspection providers that he had been legally obliged to create when Ofsted was first established in 1992 - when he was deputy director of inspection - was “almost destined to lead to inconsistency”.

He also acknowledged that human judgement inevitably entailed some inconsistency. “The question is, how do you ensure that subjectivity is at the minimum possible level?” he said.

Risk-based and proportionate inspection and the focus on the quality of leadership and teaching introduced under the present chief inspector, Sir Michael Wilshaw, was also “positive”, Sir Mike added.

He warned that parents would resist any attempt to deprive them of the information currently provided by Ofsted. “If you remove that from them there would be an outcry,” he said. “The genie is out of the bottle. You can’t push it back in and put the cork on. This will not happen and should not happen. But I think there is an interesting discussion to be had.”

Brian Lightman, general secretary of the Association of School and College Leaders, said: “It is important that data is taken into consideration but it needs to be much broader than that. Hopefully bringing Ofsted inspection teams in-house will address the problem of consistency.”

An Ofsted spokesperson said: “We do not always get it right. However, we are confident that our quality assurance procedures are strong and where we make mistakes we will put it right. By bringing all school inspection arrangements directly in-house from September, there will be more opportunity to improve quality through training and quality assurance.”

The spokesperson added that inspectors took data into account but only as part of a “broad range of evidence including outcomes for learners, the quality of teaching, learning and assessment and effectiveness of leadership and management”.