Dynamic interactions in contentious episodes: social movements, industry, and political parties in the contention over Heathrow’s third runway

While the literature on dynamics of contention has proliferated, its focus on movement onset, mobilisation, and outcomes could be used to understand interactions between actors during episodes of contention. While the authors of Dynamics of Contention acknowledge the importance of these interactions, more insight is needed into what shapes these relations and how they change over time. Here, an attempt is made to test the dynamic model as it pertains to interactions, utilising the case of the proposed third runway at Heathrow airport, which included a variety of environmental campaigners, powerful corporations, political actors and parties, and a countermovement. The campaign is broken down into phases that represent the predominant interactions between actors, and the process of phase changes is explained using a process-tracing approach. The findings highlight the importance of cognitive mechanisms over objective factors. However, explanations offered by more static models retain some explanatory power and therefore should not be discarded altogether.