By Mark Easton
BBC home editor
Bob Ainsworth had been told the research was "premature"
A Cabinet minister has been accused of wasting millions of pounds of public money by sanctioning a research project that could not evaluate anything.
As a Home Office minister in 2002, the Defence Secretary Bob Ainsworth signed off a £6m evaluation of a drugs prevention programme in schools.
The report's findings, published on a BBC blog earlier this month, said it was unable to draw "any conclusions".
It has now emerged Mr Ainsworth was warned of such an outcome.
The results of the evaluation, named "Blueprint", concluded its own design "was not sufficiently robust to allow an evaluation of impact and outcomes".
The report went on to say it could not "draw any conclusions on the efficacy of Blueprint in comparison to existing drug education programmes".
However, academic advisers had attempted to block the evaluation before it began, telling Mr Ainsworth that to conduct the research would be "premature".
In an e-mail sent to the BBC, one of the advisers, Professor Sheila Bird, said she and her colleagues thought they had "headed off the waste of public funds by sound analysis".
"I/we thought the decision-making so obvious = NOT to go ahead that we did not assiduously follow-up to ensure that the OBVIOUS decision was actually made!" she wrote.
In a statement, the Home Office said: "The Blueprint programme has helped to raise and improve our understanding about the delivery of drug education in schools."
But it admitted the episode had "clearly highlighted some of the key challenges to delivery of evidence-based drug education".
The Home Office was piloting a new system of drugs education based on an American model called Star.
Ministers wanted to see whether the apparent success of the US system in going beyond the classroom to involve parents, local media and other agencies would work in secondary schools in England.
However, before the pilot began, the Home Office was advised "the effectiveness of project Star as set out in the publicity material is not supported by published evidence".
The academic analysis went on to say the "effect sizes
are much more modest than those claimed".
Ministers were told the only way to demonstrate even modest gains from the approach was to dramatically increase the size of the sample.
Even then, the advisers reported, the "effect-size" was likely be in the order of 0.06%.
Their report concluded it would be "premature for the Blueprint team to launch an evaluation of an intervention based closely on the Star project from the USA".
The Home Office has confirmed Mr Ainsworth gave the go-ahead for the multi-million pound evaluation.
He told Parliament that US prevention programmes "with the greatest impact on behaviour" provided the "evidence" for the Blueprint project.
The evaluation, he said, would "determine whether elements of US programmes
have potential to be effective in reducing drug use".
Mr Ainsworth has so far been unavailable for comment.