The UK Royal Commission on Environmental Pollution, first appointed in 1970 and abolished in 2011, has been credited with
important developments in environmental policy and legislation. This article examines the Commission's influence in the context
of wider questions about expertise and policy formation in modern democratic societies. After presenting a brief biography
of the Commission, it sets out four different ways in which the role of expert advisory bodies has been conceptualised. It
then examines the circumstances in which the Commission exerted influence and identifies the practices and characteristics
that helped build its reputation and enabled it to have effect. Especially significant were its composition as a ‘committee
of experts’, its autonomy, its positioning within networks, and its endurance over four, formative decades for environmental
policy. The analysis suggests that influence might be best thought of in terms of a continuum of different effects, that advisory
bodies can simultaneously perform multiple roles, and that relations between expertise and policy are necessarily both complex
and contingent. Finally, some thoughts are offered on the Commission's demise and on the tensions that have to be negotiated
in considering the future of expert advice.