In 1985, the Thatcher Conservative Government granted the newly deregulated mobile-phone companies permitted development rights to erect telecommunications masts up to 15 in in height. This dilution of planning control led to a proliferation of insensitively sited mobile-phone masts across the United Kingdom, prompting large-scale public hostility. After the publication of the Stewart Report in 2000, which pointed to the possible risks to people's psychological health from antennae radiation emissions, the newly devolved planning administrations of the United Kingdom conducted reviews of these permitted development rights. The author examines these reviews and the decisions that emerged from them. It is argued that the differentiated approach to mobile phone mast control that has resulted represents an early and important departure from what was, arguably, a unified planning system within the United Kingdom.