A Channel 4 News investigation reveals exam boards making money from their own mistakes, how state schools are more likely to lose out, and the man who raised the alarm is suspended.

Please wait while this video loads. If it doesn't load after a few seconds you may need to have Adobe Flash installed.

A senior exam board supervisor has been suspended for exposing errors in the way last year's GCSE and A-level exams were marked. As part of an exclusive Channel 4 News investigation into exam marking, he revealed worrying mistakes in simple addition, which in some cases will have led to some pupils getting the wrong grade.

Not only is there evidence of careless marking where examiners have simply added up the marks incorrectly, but in one case those in charge seemed willing to turn a blind eye to mistakes.

Channel 4 News can also reveal the amount that the three main exam boards charged schools for re-marking their own papers - an estimated £5.5m. And while every student can be affected, state schools are less likely to have available funds to pay the costs of a re-mark, which range from £23 up to £60 per paper.

Whistleblower suspended

David Leitch, a senior supervisor at the exam board OCR, first became aware of the problems when he found mistakes in the final scores of a hundred exam scripts, during a routine clerical check requested by schools.

His team started to make supplementary checks on additional scripts by the same markers – and found hundreds more papers with errors. But when he told his bosses, he was ordered to stop the checks and to inform only those schools who had specifically asked for a re-mark. He has now been suspended.

Unhappy with the decision not to pursue the mistakes, he reported his findings to the regulator Ofqual. As a result, some marks were corrected but other affected schools were left in the dark – until now.

Mr Leitch was unhappy with both his superiors' and Ofqual's responses and took it upon himself to email 30 schools last week, telling them about the mistakes. He has identified dozens of papers where the marking error is so great – it has potentially meant a pupil being given a lower overall grade.

In the coming days, students who trusted the exam boards may finally discover their real marks – marks which up until now the authorities had decided to keep from them.

Read more: GCSE and A-Level exam re-marking Q+A

Examiners under pressure

However Mr Leitch is not alone in his dissatisfaction with the system. The exam insiders who have spoken to Channel 4 News describe a process where errors seem almost inevitable.

"If you want to earn a professional wage – which I’d say is £20 an hour – you’re looking at marking eight scripts an hour," said Pete, a teacher who will be marking A-levels this summer. "That isn't enough time to give a fair deal, particularly if you’re an inexperienced examiner. The fastest I mark is seven scripts an hour."

Another examiner, Malcolm, marked music A-level papers for eight years until 2010 when he gave up because of the pressure on markers to work too quickly.

"I don't think the exam boards understand the length of time it takes to do these things," he told Channel 4 News. "Mistakes are going to happen – but you might not be able to spot them."

Careless mistakes

At Magdalen College School in Oxford, there's not a lot of trust in exam marking. Last summer's GCSE results sparked a battle for justice.

Biology teacher Colin Pearson was particularly disturbed by the marking of one of this January's biology A level papers, in which a standard form of scientific notation was apparently not understood by the marker:

"This is an abbreviation that any biology teacher or professional would immediately recognise but it has been marked wrong," he said. "It raises questions about the markers subject knowledge – in particular, do they know more than the pupils whose work they are marking."

Georgia Totvanian is in her final year at Leeds university – but her life there would never have materialised if she had trusted the examiner who marked one of her final year history A-level papers. She was initially given a 'U', but it was moved to a 'B' after a re-mark.

"If I had accepted a 'U', I wouldn't have got into Leeds, probably wouldn't have got in my second choice and I would have had a 'U' on my transcript which would have looked so bad," she told Channel 4 News. "God knows where I would have ended up."

State schools disadvantaged

Magdalen is the highest performing school in the UK for GCSE results – getting accurate marks is critical to maintaining that top ranking – and that means re-marks are a routine fact of life.

But re-marks cost money – schools only have the additional fees refunded if pupils' overall grade increases, not their mark, which means schools are spending millions on getting papers marked twice.

Not all the re-marks are indicative of mis-marking. But in total, the main three exam boards charged around a £5.5m for re-marking their own papers.

However re-marks on the scale seen at private schools simply isn't a possibility for the Sacred Heart Roman Catholic School in Camberwell, south London. The headmaster, Serge Cegai, told Channel 4 News that his school's funds are being squeezed and money is tight.

"I'd like to be able to say money is no object – let them all get checked but unfortunately I can't say that. Money is an issue," he said. "Given complete freedom – I'd have twice as many appeals every year."

Read more: Examiners suspended for 'tipping-off' teachers

The most common re-marks

The exam regulator Ofqual has never collated information on re-marks by individual subject, paper and exam board, so has never before been able to determine which subjects require the most re-marks.

Channel 4 News analysed Ofqual's 'exceptions' list - where five per cent or more of the candidates requested a re-mark – and found that over half of these papers were in English, with history and music also featuring prominently.

Ofqual doesn’t see these figures as any cause for alarm, reflecting more on the subjective nature of these particular subjects.

But many examiners and teachers believe these are subjects that need a confident, experienced marker. One told Channel 4 News he believes there's simply too much toleration of wildly varying marks.

"The system is flawed – as team leader I checked in marks were within tolerance – but tolerance is three marks either way so six marks difference between the most generous and mean markers," he said. "Six raw marks difference can mean two grades."

The OCR exam board told Channel 4 News it regrets the "unacceptable mistakes" which occurred.

"We have processes for checking the total marks awarded to each script, but mistakes can occur in a system where examiners mark using pen and paper on hard copy scripts," said a spokesperson, who also apologised "unreservedly" to the schools, students and parents affected.

OCR said students taking GCSEs and A-levels this year "can be assured" that mistakes will not be tolerated.

Ofqual 'will continue to investigate'

Mr Leitch presented his findings to the education select committee, whose findings on exam marking will be released in June.

In the meantime, the exam regulator Ofqual told Channel 4 News: "When this issue first arose, last year, we asked the exam board to carry out extended checks, identify the weaknesses in its processes and to put these right in time for the January exams. It appears that new evidence may have come to light. We will continue to investigate as further issues are raised."

Speaking on Channel 4 news, the Director of Regulation at the exam watchdog Ofqual, Fiona Pethick, said she was not satisfied with the situation and would continue to look into it, adding: "if we find [exam board] OCR to be negligent, we'll take action." However she insisted the problem was not widespread.

As schools continue to dish out unprecedented sums of money to the exam boards – a record £328m last year alone – many may wonder whether they’re getting value for money.