One Norfolk school has been placed in special measures and another praised for rapid improvement, as Ofsted begins to reveal the outcomes of a focused series of inspections last month.

The education watchdog visited 28 schools over the course of just one week as it sought to discover why the county has a disproportionate number of inadequate and satisfactory – now deemed to require improvement – primary and secondary schools.

So far, a total 21 reports have been published on the Ofsted website.

They include one outstanding report, for St Mary's at Shouldham Primary School, near King's Lynn, 10 good judgments, eight schools requiring improvement, and two monitoring reports.

Cobholm Primary School at Great Yarmouth has been rated inadequate and placed in special measures by inspectors who decided the site was failing in all areas from the achievement of pupils and quality of teaching, to behaviour and leadership and management. The report says pupils are 'not prepared well enough for secondary education because their levels of skill, knowledge and understanding are way below those of other pupils their age'.

Inspectors also found attendance was well below the national average, the governing body does not challenge senior leaders enough, and action by school leaders was not bringing about improvements.

Last night Cobholm Primary's headteacher Julie Risby and chairman of governors Stephen Pullinger admitted the findings were 'disappointing' but defended the school.

Mrs Risby said the outcome was 'not unexpected' due to the 'challenging Ofsted criteria which measures all schools on the same criteria regardless of their context'.

She added: 'I know that the school has improved since the last inspection. I know staff do their very best for pupils and there are many achievements to be celebrated.'

Mr Pullinger added: 'I strongly believe the results are a harsh reflection of changes to government education policy rather than a true picture of our school.'

The Norfolk schools receiving good judgments were: Lyng Primary, Poringland Primary, Stalham Infant, Buxton Primary, Filby Primary, Corpusty Primary, St Mary's Primary at Gorleston, Stalham High, Drayton Junior and Cromer Junior.

Requires improvement (previously satisfactory): Sewell Park College, Tivetshall Primary, Great Yarmouth High, City of Norwich School, James Bradfield Primary at Stoke Ferry, Horsford Junior, and Sporle Primary.

King's Lynn Academy and North Walsham Junior School both underwent monitoring visits rather than full inspections.