This paper reports research into the effect on the UK environment of the deregulation of land development controls. One form of deregulation is granting advance approval to specified classes of small-scale development because they are considered inconsequential. Previous research has indicated that such 'permitted development' may adversely affect the natural heritage. This study systematically investigated its impact on the natural heritage of Scotland. The study canvassed the opinions of agents best placed to comment: natural heritage authority field staff, local government planners and representatives of non-governmental organizations. The results revealed concern about permitted development as a whole, and about specified classes. Despite professed concerns about sustainable development, UK planning modernization has failed to grasp the opportunity for a radical and fundamental reform of the scope of UK planning control in the context of contemporary environmental issues. Accordingly, there remains an unresolved tension between the desire to remove unnecessary state regulation of land development and the protection of the natural heritage. © 2006 University of Newcastle upon Tyne.