An exam board has apologised after teenagers taking a GCSE English literature paper were faced with an error in a question about Shakespeare's Romeo And Juliet.
Thousands of candidates may have been affected by the error, which confused the two warring families - the Capulets and the Montagues - in the famous tragedy about two star-crossed lovers.
Candidates were asked: "How does Shakespeare present the ways in which Tybalt's hatred of the Capulets influences the outcome of the play?"
But Tybalt is Juliet's cousin and a Capulet, so the question should have referred to his hatred of the Montagues.
In a statement, a spokesman for the OCR exam board, which set the paper, said: "We're aware of an error in today's OCR GCSE English Literature paper.
"We apologise and will put things right when the exam is marked and graded so no student need worry about being disadvantaged.
"We are investigating as a matter of urgency how this got through our assurance processes."
Brighton College headteacher Richard Cairns, headmaster of Brighton College said it is "hugely important" that OCR reassure pupils immediately that they will not be disadvantaged.
"It beggars belief that these things are not checked properly," he said.
The question is one of two that students could choose to answer as part of the paper.
It is understood that around 14,000 students were sitting the paper and could have been affected.
Hundreds of thousands of teenagers across England, Wales and Northern Ireland are currently sitting GCSE papers in the annual summer exams season.
This includes new exams in English and maths, which will be marked using a 9-1 system, with 9 the highest grade.