This article uses the history of broadcasting to advance historical understanding of the relationship between Britain and apartheid South Africa, and makes a broader argument about the ways in which the British state understood and engaged the postcolonial world. It uses Trilling's idea of ‘the liberal imagination’ to explain the limited British challenges to apartheid, and the sustained close relations between the two countries. Covering the lifespan of the apartheid regime, it probes the conflicts and tensions which shaped the British presentation of apartheid on television and radio, both on the BBC and independent networks. Looking in depth at broadcasters' interactions with both states, as well as with activists, pressure groups and the public, it argues that Britain's approach to South Africa was significantly shaped by a self-image fashioned in the British Empire. This self-image enabled an empathetic engagement with South Africa, which was constructed, despite the brutality of apartheid, as familiar and reasonable. Ultimately, the article argues that the British ‘liberal imagination’ played a defining role in undermining opposition to apartheid throughout the regime's existence, creating an environment where the unreasonable and abhorrent nature of apartheid was neither fully understood nor challenged by any British government.