Subtle distinction: they didn't show those tests on the aired episode. As a few clip shows have gone to pains to point out, that doesn't mean the tests were not carried out, it just means the producers didn't think they made great TV compared to the other stuff.

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"The very powerful and the very stupid have one thing in common: They don't alter their views to fit the facts, they alter the facts to fit their views." The Doctor, Doctor Who: The Face of Evil.