Ed Miliband UK general election
Britain's opposition Labour Party leader Ed Miliband delivers an election speech to supporters at the Royal Horticultural Halls in London, Britain May 2, 2015. REUTERS/Stefan Wermuth

LONDON (Reuters) - If Ed Miliband is to win power, he must pull off one of the most striking metamorphoses of recent British elections: convince millions of voters that "Red Ed", a self-confessed socialist geek, can be trusted to lead the world's fifth largest economy.

In a change that has confounded Prime Minister David Cameron's Conservatives, Miliband has already shed some of his social awkwardness and pitched a resilient, more human face, even laughing at some of his own imperfections.

Cast by opponents as a dangerous London socialist out of touch with the real world, Miliband is gambling that British politics has atomized, crumbling the middle ground and opening up space for less gleaming politicians.

That hasn't stopped him polishing his image ahead of the May 7 election in an attempt to shed what opponents say is a fatal flaw: the view he is just too wonky to lead the country.

"He's got a better suit, got a better shirt, he's presenting himself better, his hair is better, he's taking more interest in how he's appearing in the public eye," said multi-millionaire businessman David Abrahams, a former Labour Party donor.

Such is the increase in Miliband's stature that he held his own against Britain's most flamboyant politician, London Mayor Boris Johnson, in a joint interview less than two weeks before the election.

"Don’t get rattled," an assured Miliband told Johnson, who appeared unprepared for a Miliband who mixed a steely gaze with a good natured dismissal of the man the Conservatives hope can push Cameron ahead in the polls.

Miliband's tough past year included a chaotic visit to Scotland where he was heckled by opponents in an independence referendum, a speech at the Labour conference where he forgot to mention the deficit and a failed plot to oust him as leader.

But because the Conservatives made his perceived lack of stature the heart of their campaign, he has flummoxed them by withstanding their attacks.

"People have thrown a lot at me over four and a half years but I am a pretty resilient guy and I’ve been underestimated at every turn," he said early in the campaign.

FORREST GUMP EATS A BACON SANDWICH

Miliband's path to becoming prime minister was far from secure when in 2010, aged 40, the son of Jewish immigrants won the battle to replace Gordon Brown as party leader.

He was up against his more experienced elder brother David, foreign minister in the outgoing government. But by spurning the pro-business "New Labour" legacy of former Prime Minister Tony Blair, Ed secured the support of trade unions. David Miliband led through three inconclusive rounds of party voting, but Ed won by a hair in the fourth.

Former Labour leader Neil Kinnock, a veteran leftist who lost two elections in 1987 and 1992, told supporters: "We've got our party back."

But if Labour's left wing was happy at his victory, so were the Conservatives. Such was Miliband's perceived electoral weakness that Cameron's finance minister and election strategist, George Osborne, is said to have fallen on his knees when he heard the news and shouted: "Yes, Yes, Yes!"

Miliband's persona was already an object of ridicule. During the leadership battle, some Labour opponents cast him as Forrest Gump, the simpleton played by Tom Hanks in a Hollywood film, who unwittingly pops up at key moments in U.S. history.

Opponents would continue to seize on Miliband's looks and mannerisms, comparing him to TV's hapless oddball Mr Bean. A cartoonist for the Times newspaper began drawing him as the absent-minded inventor Wallace from the "Wallace and Grommit" movies. Press mockery of his appearance reached a nadir after he was photographed grimacing oddly while eating a bacon sandwich.

He has responded by painting his lack of polish as a virtue.

"David Cameron is a very sophisticated and successful exponent of a politics driven by image. I am not going to be able to compete with that. And I don't intend to. I want to offer something different," he said in a speech last year.

"I am not from central casting. You can find people who are more square-jawed. More chiseled. Look less like Wallace," he said to laughter. "You could probably even find people who look better eating a bacon sandwich."

Asked last month if he was a "geek", he said: "I plead guilty... I’m proud." He said he had never downed a pint of beer in one, and admitted weeping over last year's film Pride, about lesbian and gay activists who help striking coal miners.

With the election finally approaching, his earnest nerdiness seems actually to have earned unlikely fans.

On Twitter, some teenage girls have taken to swooning over pictures of him and superimposing his face onto the bodies of sex-symbols like James Bond actor Daniel Craig - a trend Miliband said even his own wife found hard to fathom.

Last week Miliband took the risk of giving an interview to Russell Brand, a foul-mouthed comedian who has urged people not to vote. Cameron called it a "joke", but Miliband's sincerity came off well. He defended the interview as a way to engage with young people who might shun politics.

"TRADITIONAL RESULT?"

Miliband's pitch to voters is that most people are worse off than they were five years ago, while the very wealthy have become richer, a stance that has drawn him to the left.

Some of his rhetoric about "predatory" capitalism would have been unthinkable under pro-business Blair. He has promised higher top tax rates and fewer tax loopholes for the rich, and price caps on energy utilities and property rentals.

Corporate executives have written open letters to oppose him. Labour says many of them are just rich people defending their personal perks.

Blair himself suggested in December that Miliband could damage his electoral chances by steering his party to the left. A traditional left versus right battle would have "the traditional result" - the Conservatives would win. The former Labour prime minister has since insisted his comments were taken out of context and he fully backs Miliband.

Miliband's advisers say such talk of left and right is outdated and oversimplifies an electorate transformed by the economic crisis. A wide spectrum of voters, whatever their views on other issues, are angry about wage stagnation, inequality and tax avoidance.

Still, even if he fixes his image and is correct about the change in the political winds, Miliband is far behind the Conservatives when voters are asked about economic credentials.

In a tacit admission that his party is seen by many as a spendthrift threat to the economy, his party manifesto launch focused almost exclusively on a pledge to the cut the deficit.

"Page 1, line 1, sets out Labour’s Budget Responsibility Commitment: A clear vow to protect our nation’s finances," he told cheering activists at the event inside a freezing former television studio in Manchester in April.

Just down the road in Manchester's city-center Piccadilly Gardens, Jamie Bowden, an ex-soldier who said he always used to vote Labour until the 2008 financial crisis cost him his job, expressed his doubts.

"That recession - for me it was a nasty kick in the teeth. For that, Labour are just too irresponsible, that's the thing with them," said Bowden, rolling a cigarette perched on the edge of a concrete fountain. "How can I say it without sounding patronizing? I don't think he's up to the job."

(Additional reporting by Andrew Osborn, Kate Holton, Kylie MacLellan; Editing by Peter Graff)