Without the transcripts, it would have been impossible to determine relevance.

FORBES: co-founder Sergey Brin

Ms Frederick told BBC News that she did not understand why the full report should be confidential and that it would easy enough to publish the transcripts without the details of the schools and individuals who gave the interviews.

BBC: Heads challenge Ofqual to publish all GCSE grade research

Without being briefed about what was in the transcripts, they had little to go on.

BBC: Q&A: Omagh GCHQ intelligence