Ofsted’s former chief inspector is calling for the watchdog to spend fewer resources on highly rated schools by cutting the length of their inspections by up to three-quarters.

Christine Gilbert wants the inspectorate, which she left last year, to spend as little as half a day checking the self-evaluations of schools that have previously been rated “good” or “outstanding”, if the institutions are confident that standards are being maintained.

If a school’s procedures are up to scratch, the inspectors could endorse the judgement and leave. If not, they could then conduct a full inspection, Ms Gilbert says. Under the current regime, inspectors typically spend two days in a school previously rated “good”.

For “outstanding” schools, which have been spared routine inspections since last May, it would mean a return to visits from inspectors - albeit potentially very brief ones - every five years.

Ms Gilbert believes her idea would allow Ofsted to focus more on schools that are not doing so well.

“The chief inspector has signalled his intention to increase the frequency of inspection for satisfactory and inadequate schools,” she writes in a National College for School Leadership paper published last week. “This frees up resources to enable him to do this more rapidly.”

Brian Lightman, general secretary of the Association of School and College Leaders, said the change would be a “very welcome step”.

“Inspectors can’t check every aspect of a school’s work anyway,” he said. “But they can look at the quality of a school’s self-evaluation and if they find it’s effective, they shouldn’t need to look further. I think this would be a very big step towards intelligent accountability.”

Ms Gilbert said that, to pass muster, schools would need to show that their self-assessment included some external scrutiny by making use of the opinions of staff from other schools. Her paper gives the example of Challenge Partners, a collaborative network of more than 70 schools that are already conducting Ofsted-style reviews of each other’s progress.

Both Ms Gilbert and current chief inspector Sir Michael Wilshaw have expressed concerns about “outstanding” schools being exempt from routine inspections. Ofsted figures published last year show that two-fifths of the top-rated schools were downgraded on re-inspection.

`Towards a self-improving system: the role of school accountability’ by Christine Gilbert is available at www.nationalcollege.org.uk

OFSTED’S TOUGH NEW REGIME JUST GOT TOUGHER

Ofsted’s new inspection regime has proved to be much tougher on schools than official figures released last month suggested.

The watchdog originally announced that 9 per cent of the schools it inspected between January and March were judged inadequate and failed. It has now admitted that the real figure was 13 per cent of the 2,075 state schools it visited during those three months of its new inspection framework.

Verdicts from 111 schools were missing from the original statistics, a disproportionate number of which were failed. The news is likely to reignite fears about the severity of the framework.

The missing reports had not been finalised by the 1 May cut-off date for the original statistics. But Ofsted made no mention of this when they were first released. They only came to light because headteachers’ leaders noticed a sharp drop in the proportion of schools being failed between January and March.

Russell Hobby, general secretary of the NAHT heads’ union, had feared the fall might have been caused by the inspectorate deliberately trying to manage the high number of schools it was failing.

He now accepts that this was not the case. “On the other hand,” he added, “this does mean the number of schools being put into categories (being failed) is higher then we thought and Ofsted’s regime is tougher than it originally portrayed.”

The new figures show that 7 per cent of schools inspected between January and March were judged outstanding, 48 per cent good and 32 per cent satisfactory. The equivalent percentages during the 2010-11 academic year under the previous framework were 11, 46 and 38, with just 6 per cent judged inadequate.