Local votes, national forecasts – using local government by-elections in Britain to estimate party support

In the wake of the debacle suffered by the opinion polls at the 1992 British general election, we developed a model for estimating national party support based not on the expressed preferences of electors but on how they actually behaved in the ballot box when voting in local government elections. This model proved successful in forecasting the outcome of annual local elections in each of four years, but was less accurate when tested retrospectively against the result of the 1992 general election. In 1997, however, it did correctly forecast both the Labour and Conservative general election shares of the vote and the winning party's margin in the popular vote. In doing so it out-performed all the eve of election opinion polls.