Campaigning at the district level can deliver electoral payoffs in a range of countries despite variations in electoral systems. However, effects may not be consistent. Campaigns do not occur in a vacuum, and contextual factors, exogenous to the campaign activity itself, may have a significant effect on the level of their electoral impact. The 2015 General Election in Britain is a particularly interesting case as there was a key contextual factor which could impact significantly on the effectiveness of the parties’ campaigns; the electoral unpopularity of the Liberal Democrats. Using a unique new dataset, this article assesses the contextual impact of party equilibrium at both national and district levels on campaign effectiveness. It represents the first attempt on a large scale to systematically assess the impact of party popularity on campaign effectiveness and demonstrates at both national and district levels the importance of contextual effects on election campaigns.