Histories of British broadcasting suggest that the BBC monopoly was never seriously challenged until the coming of ITV in 1955. Crossing the Ether counters this view, telling the story of commercial radio's first challenge to the Public Service monopoly between 1930 and 1939. In the telling, this account provides substantial primary evidence that radio in Britain during the 1930s was a battleground between continental-based stations, run by British and American commercial interests, and the BBC, beset by paternalistic and sabbatarian principles.