Ensuring that there are enough examiners in the system is a common goal for schools and exam boards, but there is far less agreement over who should be marking these high-stakes tests.

Exam boards insist that the vast majority of examiners are serving teachers - but adverts calling on PhD and PGCE students to mark exams this summer caused concern to some in the profession.

“There was a feeling by some that it was a bums on seats game, rather than [opting for] a quality examiner,” Anne Heavey, education policy adviser of the NEU teaching union, says.

And some are worried about the number of years that teachers have racked up in the classroom before being allowed to examine. “I think there are fewer experienced teachers doing marking than used to be the case,” Jim Skinner, chief executive of the Grammar School Heads’ Association (GSHA), adds.

It is difficult to know whether these concerns are valid, as there is no recent information available revealing the background of GCSE and A-level examiners. The last survey of examiners - carried out by exams regulator Ofqual - was more than four years ago.

Paula Goddard, a senior examiner and fellow of the Chartered Institute of Educational Assessors, says: “To recruit more people to become examiners, the industry really needs a proper understanding of who and why they are doing it.”

She adds: “They really need to delve down deeper now and not just assume that teachers will come in at the last minute to save the day. I think that time has gone.”

‘Cast the net wider’

It is understood that AQA English examiners were offered up to double the standard fee to take on additional scripts late in the marking cycle this year - because there were still tens of thousands of scripts to be marked at the end of July. AQA says that there was never any risk of marking not being completed on time.

Goddard thinks exam boards should “cast their net wider” to include teachers who may have recently left the classroom because of maternity leave or retirement - as well as other experts in a subject who may not come from a teaching background.

The lack of publicly available data also means that it is hard to know what proportion of examiners are based in independent schools, and how many work in state schools.

The Ofqual survey, from 2013, found that most (54 per cent) of the respondents worked or had worked in comprehensive schools and 15 per cent had worked in independent schools. The figures matter because many believe examiners benefit from useful insight into the marking process that can give their pupils an advantage.

And independent school teachers may have more incentives to become examiners. For example, many of their schools have shorter terms, giving teachers more time to examine.

Shaun Fenton, head of the independent Reigate Grammar School, also thinks that teachers in his sector face less workload pressure. “We have a little bit more breathing space - free of inspection pressures - and we have more resources,” acknowledges Fenton, who has also been a headteacher of state schools.

Becoming an examiner is part of the school’s professional development programme, offering greater chances of promotion.

Some independent schools, such as Brighton College, also hand extra pay to teachers who mark exams.

Antony Clark, headmaster of Malvern College, says he would consider introducing payments in future as a result of concerns about marking. “It would be helpful to have more [examiners], because you do get an inside track into the way things are perceived. You do as an examiner understand the sort of trends that are developing.”

But with the current funding pressures in the state sector, it is very unlikely that the majority of schools will be able to replicate this offer.

“It is definitely not a level playing field,” Heavey says. “If senior leaders can find ways to support teachers to be markers, whether it is finding space or time to do that marking duty, then that could be a really positive thing. But this can also come down to money,” she adds.

A spokesperson for the Joint Council for Qualifications, which represents exam boards, says: “Teachers play a vital role in the assessment system with around 50,000 examining each year.

“Although payment is a factor in why some teachers examine, the majority tell us that they value the continual professional development it gives them and welcome the opportunity to be part of the assessment system that sees their students getting the grades they have helped them work towards.”

@Eleanor_Busby