From The Philosophy of Evidence-Based Medicine:

Archie Cochrane (who inspired the creation of the Cochrane Collaboration) explained what happened when he reported the preliminary results of a trial that compared home versus hospital treatment for varicose veins. The Medical Research Council gave its ethical approval, but cardiologists in the planned location of the trial (Cardiff) refused to take part because they were certain, based on their expertise, that hospital treatment was far superior…

Eventually Cochrane succeeded at beginning the trial in Bristol. Six months into the trial, the ethics committee called on Cochrane to compile and report on the preliminary results. At that stage, home care showed a slight but not statistically significant benefit. Cochrane, however, decided to play a trick on his colleagues: he prepared two reports, one with the actual number of deaths, and one with the number reversed. The rest of the story is best told from Cochrane’s perspective:

“As we were going into the committee, in the anteroom, I showed some cardiologists the results. They were vociferous in their abuse: ‘Archie,’ they said, ‘we always thought you were unethical. You must stop the trial at once.’ I let them have their way for some time and then apologised and gave them the true results, challenging them to say, as vehemently, that coronary care units should be stopped immediately. There was dead silence…”