A new electronic weapon in the war against exam cheats was unveiled by one of the big three awarding bodies today.
From this summer, pupils and schools who try to con their way through GCSEs and A-levels will face detection by software developed by Cambridge Assessment, parent company of the OCR exam board.
The system extends a statistical technique, already used to catch out cheats in multiple choice tests, to exam essay questions.
It does not involve the actual text of candidates' answers. But data from computerised on-screen exam marking allows the software to instantly compare where exactly each candidate gained the marks available for their essays.
A-level English literature candidates, for example, could pick up different marks for the way they present their arguments, their skills of analysis and their knowledge and understanding of texts.
Where two or more scripts from the same school or college have achieved suspiciously similar patterns of marks the system will flag the papers up for further investigation.
OCR's head of compliance, Stephen Hunt, said: "This new screening service fills a gap in our ability to detect malpractice and will be a handy addition to the resources used to maintain the integrity of an exam.
"The electronic screening of scripts for similarities is another of the benefits derived from the online marking of scripts."
The drive against cheating in schools has already led to all exam boards being given access to a different kind of plagiarism-detection software pioneered in universities.
Since May 2008 they have been able to use it to analyse pupils' written coursework by comparing submitted text with writing on the internet and databases of other material, so that copied work can be highlighted.
A growing number of schools also use the software.
Ofqual supports the new Cambridge system. "The message is very clear, the net is closing in on would-be cheats," a spokesperson for the exams watchdog said.
"It is not worth the risk. While the overall proportion of candidates penalised for cheating is very low, we welcome any additional detection measures that awarding organisations can put in place."
Cambridge Assessment said its system was aimed at detecting and deterring malpractice from both individual candidates and teachers and schools.
Association of School and College Leaders general secretary Brian Lightman said school-level exam cheating was "very, very unusual". But he added: "For those people who might be tempted to try that sort of cheating, this should act as a deterrent and eliminate it completely."
The system will also be used by University of Cambridge International Examinations, which offers qualifications such as the IGCSE and Pre-U.
The board's compliance unit manager Ben Sennitt said: "Cambridge does not tolerate cheating. Students who cheat or assist others to cheat risk having their examination entries voided and their grades withheld."
Original headline: Software `closes the net' on exam cheats