"Somewhere flash but discreet" for fois gras and chateaubriand with expensive wine poured from a decanter, was the focus group's aggrieved response.

So what about Ed Miliband?

"Exactly the same," said one. Another "can't imagine him in a pub. He doesn't strike me as someone who ever goes out or has the slightest bit of fun, ever".

A month before the election, the UK's two prospective PMs are not viewed very kindly by their prospective electors.

Cameron is widely perceived as a Notting Hill elitist, who promised a kinder, greener Conservatism but delivered fairly standard Tory fare of public service cuts and tax breaks for the well-off, and whose plan for the next five years is explicitly more of the same. His air of genial arrogance appeals to some as prime ministerial, but emphatically not to others.

Miliband – so the standard narrative goes – knifed his brother for the Labour leadership, failed to convincingly eat a bacon sandwich, and reminds everyone of Wallace from Wallace and Gromit. He's the Rubik's Cube-solving geek who on radio this week confessed to being "very good" at '80s video game Manic Miner – and this was hailed as a PR triumph (relative to previous efforts).

And there you have some of the many reasons the UK is heading for what informed commentators are calling the most unpredictable general election in decades.

The electorate don't think much of the two major parties, aren't particularly impressed with either of their leaders, and don't feel like giving either of them a mandate to run the country.

Nevertheless, after May 7, one of them will have to try.

"This is probably one of the hardest elections to call," says Nicola Wildash, researcher for polling company YouGov. "The main two parties are neck and neck, and not getting above 40 per cent (of votes), it's getting less and less likely that they'll go on to win a majority."

Half a century ago, about 80 per cent of the UK public voted in general elections for Conservative or Labour. Now, less than 40 per cent of the country vote for either.

"The way you would have predicted an election in the past is not adequate this time," Wildash admits. "Historical precedent isn't as clear cut. We've got so many unknown factors, so many pieces to this puzzle."

Roughly, the Tories have lost a little support since 2010 (when they failed to win a majority of seats) and can count on just over one-third of voters, Labour have gained a little support since 2010 (when they were emphatically dumped from government) and can count on just over one-third of voters.

The rest, usually, don't count. The UK's first-past-the-post system kneecaps the smaller parties. For example, since 1945 the Liberal Democrats have won 14 per cent of all votes cast, but just 3 per cent of seats.

But this time around, the smaller parties are louder than ever – not so much for the seats they'll win (with the exception of the Scottish National Party: not many), but for the disillusioned votes they'll sap from the big two.

That's why the campaign's only leaders' TV debate, on Thursday night, looked like The Weakest Link. Four men and three women lined up at podiums, with accents spanning Welsh, Scottish, English and Australian (Greens leader Natalie Bennett), and grumpily talked over each other for two hours.

By the end of it, Miliband was still awkward, Cameron was still promising more of the same, and neither had landed a punch that could swing an election. In snap polls after the debate, many scored SNP's Nicola Sturgeon over Miliband, and UKIP's Nigel Farage over Cameron.

But both major parties were quietly happy in the wash-up, because it laid a base for the type of campaign they're planning. The Australian political strategist for the Conservatives, Lynton Crosby, had Cameron under instructions to be technical and unemotional – to come across as a 'safe pair of hands', a statesman among the brawlers and small fry.

His robotic repetition of 'long term economic plan' is going to grate right up until election day, then echo in the ballot box, according to the plan.

As for Miliband, the challenge was to make him a credible alternative. Low expectations can work in his favour – every time he has a competent campaign appearance the polls bounce in recognition, as he becomes a safer option for a protest against austerity. When he eyeballed the debate camera lens and promised to fix the National Health Service, some Tweeted 'stop staring at me in my pyjamas', but others saw genuine passion.

Each side is settling into its message. No-one yet knows which will cut through. Will it be the austerity-masochistic, Fifty Shades of Blue story that leaves the Tories holding the whip hand, or will Britain choose 'Miliband' as its safe word?

Wildash says – as in most elections – healthcare and the economy are the two biggest issues in voters' minds. But there is particular concern this time round about the National Health Service, and whether it has suffered too much under a privatisation-friendly coalition.

Then there is the economy. In the last year or so the UK has boasted some of the best economic figures in Europe. But it's unclear whether voters believe the statistics.

"Cameron does very well on the economy, but Miliband could definitely take the angle that people aren't feeling it in their back pockets," Wildash said. "Miliband is going to say the rich are getting richer and the poor poorer, how can the economy be improving if you're not feeling it in you're your wages and cost of living?"

This week saw both parties rehearse their economic arguments. The Conservatives produced a laundry list of business leaders who backed their economic plan, while Labour promised to end the plague of zero-hour-contracts that take the security out of employment.

Tory pollster Lord Ashcroft has been paying particular attention to the swing seats and undecided voters.

He found some scepticism on Labour's promise to fix social security and the health service while also cutting the deficit. But he also found that Labour's message, that the economic recovery wasn't benefiting the bulk of the working population, had hit a chord.

People are finding things hard, Ashcroft wrote, making comments such as "utility bills are horrendous, if they've gone down I haven't noticed", and there was a belief that the economic good news was only good news for the top end of town.

"I just feel nothing has changed for years," said one.

Then, there's immigration.

"When we ask people what is the most important issue to the country, immigration is No. 1," Wildash says. "It beats the economy."

This unusual prominence is a tribute to the stunning success of charismatic, chain-smoking, pint-swilling Farage and the UKIP party he leads. In 2010 they were a barely a blip on the radar, since then they have dominated European elections in the UK, put members on councils across England, attracted Conservative defectors and won two by-elections, with a mantra of leaving the EU in order to slash the number of European immigrants.

But YouGov are seeing a downward trend in their vote – and expect it was a temporary home for a protest vote that should drift back to the major parties (two-to-one back to the Conservatives they deserted).

"If you ask voters what is the most important issue to affect you and your family, (immigration) drops to fifth place, from 50 per cent to 15 per cent," Wildash says. "I think people vote for themselves. They ask if they are happy with themselves, their family and community. They become a bit more selfish when they are actually in the polling booth."

Most pollsters, including YouGov and Ashcroft, are pretty certain no party will claim a majority of seats after the election.

A team from the London School of Economics calculated that the least likely result of the election is that one party will win a majority of seats.

Pollsters don't even agree which party will win more seats. One analyst gave Labour a 77 per cent chance of being the biggest party, another gave them a 38 per cent chance.

The third-biggest bloc is likely to be the SNP, riding a wave of post-Scottish-referendum disillusionment with Westminster, followed by the Liberal-Democrats, decimated but not eliminated by the backlash over five years in coalition.

The possible new coalition permutations are eye-watering. The most likely result, says the LSE, is that the party with the largest number of seats has no possible two-party coalition partner (excluding a Europe-style grand Coalition, which is about as likely as Farage going teetotal).

"In short, there is a good chance that we are heading for a very messy hung parliament in May," the LSE team concluded.