The Royal Family has denied a claim that Prince Harry cheated in his art A-level.
Prince Harry got a B for his art A-level
The allegation is said to have been made by a former teacher at Eton who is taking the college to an industrial tribunal claiming unfair dismissal.
Sarah Forsyth reportedly said a senior master told her to help the prince answer questions enabling him to achieve a B grade.
Clarence House said an investigation by an examination board had concluded there had been no cheating.
Ms Forsyth will make her allegations when she appears at the tribunal on Monday, the News of the World said.
The newspaper reported that the former teacher claims she was asked to assist Prince Harry to compile his AS-level art coursework journal. The marks from this discipline counted towards his final A-level grade.
The private school's board has denied the allegations.
Teachers sent the prince's 2002 exam paper to be double-checked anonymously by the exam board, but no irregularities were discovered.
The board, Edexcel, said in a statement that it did not comment on individuals but could confirm that in 2003 Eton contacted it about an allegation of cheating against a candidate.
"All such complaints are treated very seriously and always thoroughly investigated by experienced personnel," the board said.
"In this particular instance there was no evidence to support the claim. It was found to be unsubstantiated and the file closed."
The 20-year-old royal, whose other A-level pass was a D in geography, needed reasonable grades in order to help him qualify for Sandhurst military academy, where he will begin his army career in January.
The minimum Sandhurst entrance requirement is two A-levels and it is understood Prince Harry's military career could be at stake if one of his passes was shown to have been obtained by cheating.
A statement released by Clarence House dismissed the allegation as "unfounded".
"A full investigation into these allegations was held by the relevant exam
board which found no evidence to support the claims."
Ms Forsyth is thought to have been turned down for a staff position at the school after three years on probation, before being offered a £10,000 pay-off.
Prince Harry, who is third in line to the throne, passed his Sandhurst entrance exams in September.
The Regular Commissions Board four-day test included obstacle courses, medicals and planning exercise.