The leaders of Britain's seven main political parties went head-to-head in an unprecedented TV debate on Thursday as the nation prepares for this year's general election. Nobody is expected to win a majority when votes are cast on May 7 in what is being touted as the closest and most unpredictable race since the 1970s. Prime Minister David Cameron, of the Conservatives, narrowly topped the polls assessing who 'won' the two-hour clash against six other parties in an unusual format for Britain. Crucially, 33 per cent of the 7.4 million viewers hailed Cameron as 'the most impressive' on the subject of the economy, which lies at the heart of each party's campaign. But pollsters refuse to predict whether it will be Cameron or the Labour Party's Ed Miliband who takes the top job in an inevitable coalition after votes are cast. Scroll down for video . The build-up: Prime Minister David Cameron went head-to-head with six other party leaders in a TV debate on Thursday night in an unusual format for Britain. It comes six weeks ahead of the general election on May 7 . Neck-and-neck: Cameron was hailed as statesmanlike in the debate as he tries to edge out Miliband (right) Nicola Sturgeon, of the pro-independence Scottish National Party (SNP), was widely touted as one of the victors in the debate, which also featured the environment-focused Green Party, led by Natalie Bennett, and Wales' Plaid Cymru, led by Leanne Wood. Deputy Prime Minister Nick Clegg, leader of the Liberal Democrats, and Nigel Farage of the UK Independence Party completed the line-up. Analysts remarked that none of the leaders managed to deliver a 'killer line' that would set them apart from the other participants. 'There was clearly no knock-out blow,' said Peter Kellner of pollster YouGov. Jonny Tudor, 17, who asked one of the questions on the night, said afterwards: 'Some performed well in answer to certain questions, other performed well on different subjects, but there was no definitive winner.' A rare moment of drama came when a female audience member briefly interrupted Cameron to complain about the number of homeless people sleeping in the streets. Too close to call? Pollsters refuse to predict whether it will be the Labour Party's Ed Miliband (left) or David Cameron (right) in the top job after votes are cast. But polls named Cameron as last night's debate 'winner' Range: Nicola Sturgeon, leader of the pro-independence Scottish National Party, was touted as one of the victors. Analysts remarked that none of the seven leaders delivered a 'killer line' to stand out from the rest . Rare moment of drama: A woman stood up during the debate to heckle Cameron about homelessness . But in a result that will calm Conservative nerves, a Comres/ITV poll showed 40 per cent of voters asked afterwards judged Cameron was the most capable of leading Britain, compared to 28 per cent who named Miliband. The event was the first and only full TV debate of a campaign that has yet to stir voters, many of whom say they feel jaded despite a rising economy. It is the only time Cameron and Miliband will go head-to-head on issues of policy before votes are cast. In one of Cameron's more animated moments in an otherwise reserved performance, he pointed to his rivals, one-by-one, and said: 'What I'm hearing is more debt and more taxes, more debt and more taxes, a lot more debt and more taxes, some more debt and more taxes, and definitely more debt and more taxes.' Deputy Prime Minister Nick Clegg was forced to reference mistakes he made in the last five years in coalition . Hot topics: Immigration divided leaders, as the UK Independence Party leader Nigel Farage (pictured) insisted Britain will have to leave the European Union in order to have control over the nation's borders .
Prime Minister David Cameron faced six other party leaders .
None of the leaders are expected to land a majority in the May 7 election .
No leader delivered 'killer line' but he was 'most impressive' on economy .
Pollsters touting this election as closest since 1970s, inevitable coalition .