So what went wrong with the electoral system: the 2010 election result and the debate about electoral reform

Single-member plurality is often thought to facilitate a two-party system of alternating single-party majority government. However, no party secured an overall majority in the 2010 UK election, which was followed by the formation of the first peacetime coalition government since the 1930s. This article assesses whether this outcome was a one-off occurrence or was symptomatic of longer term changes in voting patterns in the UK that have reduced the likelihood of singe party majorities. To do so it charts trends in the level of third party support and representation, the incidence of marginal seats, and bias in the treatment of the two largest parties.