This article discusses the occupation of an oil-related structure called the Brent Spar in the British sector of the North Sea by Greenpeace protesters in 1995. Shell intended to 'dump' the buoy in the deep North Atlantic. The aftermath of the occupation and associated publicity was a change of policy about the disposal of the Spar by Shell, Europe's largest multinational company. The article considers alternative explanations for policy change - most importantly the influential propositions by Baumgartner and Tones (1993). The general importance of their work means that the opportunity is taken to set out their themes at some length, but the particular case suggests that their notion of change stemming from a redefinition of the problem may only imperfectly fit sudden policy changes of the Brent Spar type. The article argues that their 'venue shopping' concept better illuminates the case - but the significant venue change was geographical - i.e. from Britain to Germany rather than institutional - i.e. from a policy community to an issue network. The case study superficially accords with an influential body of literature in the 1980s and 1990s that sees outcomes as changing through the mobilization of a wider range of participants in issue networks, but it is argued that there is no automatic link between an expanded roster of participants and outcomes if the decisive decisionmaking power is retained in the original closed system. The case study suggests there can be an illusion of an issue network when the dominance of a policy monopoly is publicly challenged - but where decision-making power is retained among original participants.