Ozone research is usually considered a very good example for successful cooperation all along the twentieth century between a considerable number of countries on a truly global scale. The work of the British Antarctic Survey (BAS) reveals however a more complicated pattern. In order to be able to speak with authority on upper atmosphere phenomena in Antarctica, ozone researchers from the British Antarctic Survey built up their own rigid set of standard procedures and calibration methods. In particular, they refused at a certain point to communicate their ozone data to the global ozone network in order to avoid “dilution” of their robust data with measurements which they considered mostly of doubtful origin. This “closed world” strategy proved highly successful: in 1985, BAS announced the groundbreaking discovery of annual stratospheric ozone depletion above the Antarctic continent – well before other “competitors” (such as NASA’s ozone group) were able to publish on the phenomenon. Revisiting the history of this important environmental discovery may help identify quite different institutional strategies of evidence production and patterns of highly selective cooperation efforts in order to build up authority in a clearly delimitated research field.