A college says it did not release its GCSE results on Thursday because it suspects an exam board technical error led to a large drop in its results.

Eastern Daily Press: The Head of Sewell Park College, Gavin Bellamy. Picture: Denise BradleyThe Head of Sewell Park College, Gavin Bellamy. Picture: Denise Bradley (Image: Archant copyright 2011)

The concerns of Sewell Park College, Norwich, echoed other Norfolk schools whose students sat English exams set by WJEC, the Welsh exam board, and saw an unexpected number fail to achieve their expected C grades.

Sewell Park principal Gavin Bellamy said the proportion gaining at least five GCSEs at A*-C in all subjects was 58pc, 1 percentage point lower than last year.

'Within that, some subjects were extremely successful', he said. 'However, the Welsh board GCSE results for English took an unexpected drop and the result is that at this stage our five A*-C figure for English and maths is 31pc.

'The school is investigating this matter with some urgency.'

If Sewell Park's English results stand, it would be the fourth Norfolk school to fall below the government's target of at least 40pc of students gaining five or more GCSEs at A*-C, including English and maths.

Mr Bellamy said the Welsh board results contradicted another measure used by Ofsted, which showed 63pc of students improved by three levels in English since leaving primary school, compared to 57pc in 2012.

Other schools which highlighted unexpected English results from the Welsh board included Caister High, Cliff Park High in Gorleston, and Stalham High.

Stalham head Melinda Derry said: 'Ten of our students who we confidently expected to get a C grade got D or below. We will be challenging the Welsh board marks. For us, 10 students is very critical as we had a cohort of 90.' She added: 'It feels as if English results have become a lottery and the children are the casualties.'

A spokesman for WJEC said: 'WJEC uses thorough marking and awarding processes which are subject to rigorous quality assurance to ensure fairness for all candidates. A range of information is used to set grade boundaries and it is normal to see a minor shift in them from year to year. Schools and colleges should contact us as soon as possible if they have enquiries about their results.'