While staff at the Queen Elizabeth School, Wimborne, Dorset, waited for the papers to arrive, the 13 students were kept in stress-inducing isolation all morning, so that there could be no accusations of the candidates contacting pupils elsewhere in the country who would have already taken the French A-level paper.

Two of the pupils who had a maths exam scheduled for the afternoon were forced to take it in the morning instead, with only 15 minutes notice to prepare themselves, so that both exams could be taken on the same day.

A furious deputy headteacher, Eric Joint, said that the school had asked the Cambridge examination board to take the adverse impact of the wait into consideration when they came to mark the papers. This was the most "catastrophic" exam problem he had come across in 20 years of teaching, he said.

"Pupils were understandably upset," he said. "Although we tried to keep them calm, they had come to school psyched up for the exam, which is a very important event for them."

Mr Joint said that exam papers usually are delivered to the school a month before the date for sitting the paper and that he had contacted the examining board repeatedly prior to the exam date asking for them to be sent. The missing papers were finally delivered to the school by courier.