Election polling split poses dilemma

One is a near consensus view that Britain is heading for its first hung parliament since 1974 with no single party in overall control; the other sees a comfortable victory for the Conservatives over Labour.

Most pollsters, including ComRes, ICM, Ipsos-MORI, Populus and YouGov, have reported a decline in the Conservative lead since mid-January from a double digit gap last year to between around 4 and 9 percent now.

By contrast, Angus Reid Public Opinion has consistently shown the Conservatives enjoying a double digit lead since it started surveying political opinion last year.

Uncertainty generated by the polls has buffeted sterling, with traders driving the currency down 4 cents after a particularly narrow YouGov poll earlier this month, before buying it back days later on an Angus Reid poll.

The pound has fallen 6 percent against the dollar since January, in line with the decline in the Conservative lead reported by the main polling firms.

The Conservatives' sterner approach to tackling the record 178 billion pound budget deficit has found favour in financial markets. The Conservatives want to get to work on the deficit this year, while Labour's deficit reduction measures would only kick in next year.

NOT ALWAYS ACCURATE

Polling companies have been measuring the political mood since the 1930s by interviewing a small but representative sample of the population and have a good track record of predicting election outcomes.

But they have suffered failures, miscalculating the outcomes of the 1948 U.S. presidential election, Britain's 1992 national vote and the first round of France's 2002 presidential race.