Undecided voters hold key for Britain's new parliament

London // Britons will go to the polls today to vote in the closest fought election in living memory. Although opinion polls yesterday gave the Conservatives an increased lead over Prime Minister Gordon Brown's Labour Party and the Liberal Democrats, the peculiarities of the UK's first-past-the-post electoral system suggested that the nation was heading for its first hung parliament in a generation.

But nothing is, or has been, predictable in this campaign, with the fortunes of each of the parties going on something of a roller coaster ride in the past month. Most importantly, perhaps, surveys indicated that up to 40 per cent of the people casting their vote today were still undecided yesterday whom they would be supporting. If a hung parliament is the outcome by the time most of the results in the 650-seat House of Commons are declared by tomorrow morning, days of horse trading in a bid to form a government could follow. Mr Brown is hoping that he will have enough seats - even if he trails the Tories by a distance in the popular vote - to cling on to power by going into coalition with the Lib Dems.

David Cameron, the Conservative leader, is refusing to even discuss the possibility of his leading a minority government. A partnership with the Liberal Democrats would, anyway, be difficult as one of their basic demands is that proportional representation be introduced to the UK's electoral system - something the Tories have flatly ruled out. The Lib Dems, though, are enjoying widespread support for electoral reform. Under the current system, should they get a quarter of the popular vote today - which the polls predict will happen - they will end up with only an eighth of the seats in parliament.

Across the average of opinion polls this week, the Conservatives enjoyed support at 35 per cent, Labour 29 and Lib Dems 27. Translated into seats in parliament - and because Labour's votes tend to be more concentrated geographically than their rivals - this would mean Labour ends up with 272 seats, the Conservatives with 270 seats and the Lib Dems with 79 seats. The remaining 29 seats would be scattered among Scottish, Welsh and Northern Irish parties.

Labour appears to have rallied in the final days of the campaign, at the expense of the Liberal Democrats, mainly because Mr Brown has upped his game after a fairly lamentable showing in the opening fortnight of the campaign. He did not do well in the three televised debates and he complained yesterday that the campaign had concentrated too much on personalities and not enough on policies. "The novelty of television debates clouded the need for policy to be debated," he said in a BBC radio interview.

"We're making big choices about the National Health Service, schools and about jobs, industry and the economy. "I feel we have not yet discussed sufficiently the risks to the economy in the future and the need for jobs to be secure." Mr Cameron campaigned throughout the night yesterday because he "didn't want to waste any hours on the last day" before people vote in what he described as the "most important election in a generation".

He told GMTV he believed that the Conservatives were winning the big arguments, but added: "I don't want to take anything for granted, it's a very important election. It's a close election and I'm fighting for every vote right down to the wire." Asked why he thought his party's poll lead had dropped since the start of the campaign, Mr Cameron said: "I never believed this election was going to be easy. Elections are meant to be a challenge.

"The British people don't hand you the government of the country on a plate, quite rightly they are making us work for it." Nick Clegg, the leader of the Liberal Democrats, told Sky News: "There is a still a day to go, there are still lots of people who haven't decided how to vote. "This is an unbelievably important day. I'm going to work incredibly hard right down to the last minute to say to people they've got this fantastic, once in a generation opportunity to do something different."

While the Lib Dems did seem to be suffering from a classic "third party squeeze", with their rivals playing on voters' fears of a hung parliament, Mr Clegg received a small boost yesterday when psychological research showed he had the most key personality traits among the three party leaders to be the "perfect" prime minister. Prof Alex Linley, the director of the Centre of Applied Positive Psychology in Coventry, said all three party leaders showed "promise" in terms of judgement, compassion, personal responsibility, tackling problems and seeing how things can be improved.

Mr Brown was perceived to be good at tackling problems, Mr Cameron's strength was maintaining a positive outlook, while Mr Clegg was said to have good judgement, was compassionate and a "born improver". @Email:[e-mail]