Tactical voting at the 2010 British general election: rational behaviour in local contexts?

Tactical voting is an important clement of British electoral behaviour, with approximately one sixth of all voters surveyed indicating that they voted tactically at the 2010 general election. Such voting for one's second preference party rather than one's first in order to prevent a less preferred party winning in a constituency is only rational in certain circumstances, reflecting the local context and electors' perceptions of the tactical situation there. Using 2010 British Election Study Internet survey data, this paper uses three separate definitions of tactical voting (two self-defined by the respondents, one inferred from a separate indication of their preferences) to test whether rational voting models successfully predict such behaviour. The findings are very clear and consistent with the theory, for all three groups.