A government-commissioned report into whether a pregnancy test drug caused deformities is due to be released later.
But alleged victims of the drug called Primodos have already criticised the terms of reference of the report and the way it has been conducted.
There is frustration that the study, overseen by the current medicines regulator the MHRA, has not investigated regulatory failings.
Sky News understands that the Expert Working Group (EWG) set up by the Government to examine hormone pregnancy tests has been told to disregard evidence relating to regulation of the drug.
There is also frustration that the campaign group’s only representative on the panel has had to sign a confidentiality agreement and can’t discuss what was said in meetings.
Marie Lyon, chair of the Association for Children Damaged by Hormone Pregnancy Tests told Sky News: “I could go to prison if I divulge what was discussed.
“So it isn’t transparent.
“I can’t speak to our members.
“I can’t speak to any members of parliament, I can’t disclose anything to the 118 MPs who are supporting this campaign.
“It defies logic that this kind of control is placed on someone who is just trying to get justice.”
The publication comes several months after Sky News revealed that the UK regulator knew in 1975 of a potential five to one risk that the drug could cause deformities, but only warned the manufacturer, not the general public.
Documents relating to this risk were later destroyed, according to the files we uncovered from archives in Berlin.
SNP MP Hannah Bardell, who has a constituent allegedly affected, said: “The Sky documentary Primodos: The Secret Drug Scandal raises concerns that documents linking Primodos to deformed babies and premature deaths were destroyed.”
But the EWG is unlikely to explore what happened to these documents and instead only study historic scientific evidence relating to the drug. Several experts have warned Sky News that this evidence is likely to be outdated and inconclusive.
Earlier this year at a screening of the Sky News documentary, a representative of the current regulators MHRA also admitted they did not have powers to force the manufacturer Schering, now owned by Bayer, to hand over all documents relating to the drug.
Bayer denies a causal link between Primodos and birth defects and said that, after a full review, the evidence that it caused malformations was “extremely weak”.
It is far from clear whether those seeking answers will get them in the report, or even whether significant questions have been asked.