In the late 1940s, concealed random allocation was used to generate comparison groups in the British Medical Research Council’s celebrated multicentre controlled trial of streptomycin in patients with pulmonary tuberculosis (MRC 1948). In particular, the details of the allocation schedule were concealed from those entering patients into the trial.

The UK Medical Research Council’s 1948 report of a controlled trial of streptomycin for pulmonary tuberculosis was a methodological landmark because it provided detailed information about the trial, and in particular, the steps taken to prevent foreknowledge of treatment assignments.