Junior coalition parties in the British context: Explaining the Liberal Democrat collapse at the 2015 general election

The Liberal Democrats' performance in the 2015 general election provides an opportunity to examine the only case in the post-war period of a national junior coalition partner in British politics. Comparative research highlights competence, trust and leadership as three key challenges facing junior coalition parties. This article uses British Election Study data to show that the Liberal Democrats failed to convince the electorate on all three counts. The article also uses constituency-level data to examine the continued benefits of incumbency to the party and the impact of constituency campaigning. It finds that while the incumbency advantage remained for the Liberal Democrats, it was ultimately unable to mitigate the much larger national collapse.