• elections;
  • bias;
  • contest types;
  • target seats;
  • campaigns

Geography is an inherent component of the UK electoral system, and several separate geographies interact in the translation of votes into seats. Many argue that Great Britain now has a three-party system, but we show that it is dominated by three separate two-party systems because of the geographies of support for the three largest parties. At recent elections, the translation of votes into seats has substantially favoured the Labour Party. At the 2010 election, however, that advantage had largely disappeared, in both the constituencies where its main opponent was the Conservative Party candidate and those where it was the Liberal Democrat candidate. Removal of that pro-Labour bias in the former case resulted from the Conservatives' largely successful target seats campaign.