Until recently, serious study of the rationale underlying the space policy announced by the Macmillan government in May 1959, even when attempted, was hampered by the "thirty year rule". Now, knowledge of the arguments deployed by the principal players in this one area of policymaking lay and scientific civil servants, scientific advisers and ministers, academics may be of interest to students of other areas, and of contemporary British history. Although the policy-makers of the late 1950s were alive to the importance of establishing the priority of the new field, to raise this issue did not necessarily imply even the wish, let alone the ability to wield prioritisation effectively as an aid to policy-making. What is clear, however, is that policymakers were unconsciously weighting at least some of the "criteria for scientific choice" identified in the well-known science policy debate of the early 1960s.