The elements could be set to hand another advantage to Labour on polling day.

Weather forecasters are predicting that June 7 will bring with it perfect conditions - which could work in Labour's favour.

On past polling days experts have found that bad weather has tended to favour the Conservatives. Conventional wisdom suggests that traditional Labour voters tend to be deterred by rain.

With Tony Blair saying that apathy is his biggest enemy a wet and windy day could have seriously affected his chances of success.

"There's a reasonable chance of fair weather on polling day. It will be predominantly dry and sunny with some patchy cloud in some parts of the country," said a Met Office spokesman.

The theory is not as strange as it seems. According to the Met Office, May 1997 saw dry and sunny weather across England and Wales. April 1992, which saw the Conservative majority cut to 22, was dry with mostly unbroken sunshine across England and Wales.

The weather for Margaret Thatcher's third victory in June 1987 was cloudy with thunderstorms in the afternoon along a line from North Wales, through London, to north Kent.

Many places across the UK in June 1983 had light showers during the day. The polling day of May 1979 which began the Conservative government's 18-year run had cold and showery weather everywhere. The showers were mostly light but temperatures were well below normal.

The Met Office warned Tony Blair should not relax yet. "There are no guarantees as long-range predictions are still a long way out - it's really a snapshot. There is a slight lack of confidence in what the computer models from around the world are telling us. By the weekend we'll have a much better idea," he said.