Mary Creagh is a keen cyclist. When I interviewed her last year, in her role as shadow transport secretary, she went into detail about what my safest route to work would be, were I to get a bike. She does the same today, when our interview is up, encouraging me to take a riverside route.

The outsider in the Labour leadership contest, who had been expecting to be Ed Miliband’s International Development Secretary up until polling day, illustrates a lot about her career trajectory through cycling.

When growing up in Coventry, she would cycle to and from school, due to “being skint” and saving on the bus fare. Reaching Oxford to do a degree in modern languages, she was thrilled that “cycling was trendy! Finally!” After a few twists and turns around Brussels, teaching and working with small business owners back in the UK, and navigating north London as a councillor in Islington for seven years, she was elected MP for Wakefield in 2005. Now she cycles in to Westminster every day.

Her mother worked as a primary school teacher and her father was an office worker in a car factory, and both migrated from Northern Ireland and Ireland, respectively, to Coventry in the Sixties. Creagh’s journey via local government from an ordinary childhood in the West Midlands to representing a safe Labour seat in West Yorkshire leads her to describe herself as “Bootstrap Labour”.

“I've worked my way up through the party,” she says. “I started as a ward secretary, local councillor, I've led a Labour group [on the council]. I've got five years’ experience as a backbencher, where I changed legislation on the Children’s Food Bill, tried to change the law on cohabiting couples to get more justice for women, and closed the loophole on people who committed war crimes where they couldn't be prosecuted in this country . . .

“I was proud to be given a small job in the Whips' Office under Gordon Brown . . . I've also done three important jobs in shadow cabinet – environment, food and rural affairs: forests, horsemeat, floods,” she chuckles, reeling them off. “And I've done transport, and I've done international development. So I've got the broad range and depth of experience. And I've also shown that I'm a fighter. I think Britain needs a fighter.”

And Creagh will need to put up a fight during this leadership race. Surprising the Westminster village by deciding to run for the leadership – unlike her rivals, she hadn’t previously been touted as a successor to Ed Miliband – Creagh has significantly fewer public backers than the others. (We can only count five signatures).

She also announced her bid a week after the others were off the blocks, though insists she has “no idea” if they'd been planning their campaigns before the election. “I didn't go around briefing,” she says. “I didn't brief it out. So I think the press lobby was perhaps more surprised than some of my parliamentary colleagues were.”

Sipping on a cup of tea in a basement café near parliament, Creagh appears quietly determined. She is in the same distinctive red shirt and dark blazer she wears later this evening on Newsnight, where she gives a less exciting performance than when she was up against the nightmarish duo Nigel Farage and Russell Brand on Question Time last year, during which her reason and humour were much praised.

Her blue eyes look almost steely as she bats off my questions about her lacking the requisite parliamentary support (35 MPs) to be nominated. “I'm confident I'll be on the ballot paper,” she says.

What about those who say she has no chance?

“Well, they've never worked in the Whips' Office have they?”

Creagh decided to run when she was up in Wakefield the week after the election, following some phone calls over the weekend. “I talked to a few parliamentary colleagues, I was getting calls from people asking me, and I thought very hard about it . . .

“I just thought, ‘this is my duty’. I just felt very strongly it was my duty. I felt that call very clearly.”

She thinks it's time for a female leader: “We’ve got a parliamentary Labour party that is 43 per cent women, so I don't think they want to see an all-male top team either,” she says. “I think people are ready for a woman Labour leader and I think it would send a very strong signal out to the country about the way that our party's changed.”

Creagh has avoided being pigeonholed – ‘Blairite’, ‘Blue Labour’, etc – and calls such “left/right” labels “reductive”. She feels “the public are heartily sick of a Westminster-obsessed press deciding who the leader’s going to be before the competition has even started”. But this does make her pitch a little hazy.

While accepting “I am less well-known” than her opponents, she thinks this “offers the party opportunities”. She is forthright about the importance of her grassroots party experience, as opposed to a background of serving in Whitehall . Of her three rivals, two (Andy Burnham and Liz Kendalls) have been special advisers. Such a career trajectory was part of Ed Miliband’s downfall.

“What local government gave me was an understanding of how decisions that you take affect people's lives, because as a councillor you're much closer to people,” Creagh reflects. “So when you make a bad decision, people will very quickly let you know that they're not happy with that. Whether that's closing a road, whether it's contracting out certain services, you learn very quickly and you have to be fast in correcting your mistakes.

“I think in central government, we are slow, we are not dynamic – I'm talking about the whole government machine – we're not that responsive to people . . . I think councils are the seedbed of innovation in the party. And across the country, they are showing how they can get more for less; they dealt in most cases very well with the very, very harsh cuts.”

Creagh’s aim is to devolve power to the cities and regions, something informed by her transport brief – though she refuses to tell me whether or not she would like that job back if she loses.

“Good transport and good schools are the two things that people care about most when they're deciding where to live and work,” she says. “And the areas that have good schools and good transport links are the ones that increasingly now are getting ahead.”

But business is Creagh’s strongest subject. Most high-profile party figures criticising their time under Miliband have attacked Labour for seeming “anti-business”. Creagh, who taught entrepreneurship at Cranfield business school, worked as a press officer for the London Enterprise Agency, and set up a trade union branch in Brussels, is focused more on business in terms of small business owners and self-starters than launching a prawn cocktail offensive.

“I had a life before politics,” she replies, when I ask her about this background. “Not a lot of people know about my background, but I think it's important that people understand we have alienated – I think our language alienated – self-employed tradesmen, women, anyone running a small business, that the way we spoke about businesses made them feel excluded.

“If we want the great public services, the good schools, the good hospitals, the good roads – speaking as a cyclist – we have to have people running businesses and paying their taxes to enable that to happen, and creating wealth."

She links this to “unhelpful” language about attacking wealth. “Our policy on the cut to business rates didn't really land. I don't think people heard it. I think people saw the Mansion Tax as something that, although they may not live in a house that expensive, they might one day aspire to live in a house worth £2m.

“And I think the ‘producers versus predators’ language was unhelpful.”

Creagh is particularly scathing about what she sees as the Labour government’s role in the financial crash. She has already spoken out that Labour should not have been running a structural deficit before the crisis, but goes even further:

“The failure – our failure – to regulate the financial sector, which led to, well, didn't lead to it, but it was everybody's failure to regulate the financial services industry that contributed to the global financial crisis, which is where our large debt and our large deficit came from.”

But one aspect of Labour's past Creagh did agree with was Miliband's “One Nation” idea. “It’s about where we’re all going together as a country, how we’re going to make life better for working people – I think those things worked,” she says. “But the idea was dropped, and I think that was unfortunate, and is now being claimed by Cameron. And we have to reclaim, I think, the language of work – labour – the clue is in the name,” she grins.

As the only candidate to have set up a trade union, Creagh feels well-placed to do this. “I'm proud of Labour's links with the trade unions, and we'll always be the party of working people and the voice of organised labour is always going to be a very important part of our party. We also need to now be the voice of unorganised labour, of self-employed labour,” she adds.

Her endeavour to get through to working people does not translate into anti-immigration rhetoric. Although she says she would keep Labour’s policy to delay benefits to EU migrants for two years, she is adamant that the problem is perceived rather than real.

“In Wakefield, there is the perception that ‘my child can't get it and this child is getting a school place’,” she says. “Those perceptions, and the Tories’ failure on public services – whether it’s failure on the NHS, A&E, GPs – people are blaming other people. As soon as you have working people blaming other working people, it’s the Tories’ old divide and rule. We’ve got to actually show people that it is not your Polish neighbours, they haven't caused you the problem, they are paying in, they are doing their bit.”

Whether Creagh makes the ballot paper or not, her experience is refreshing. Her bootstraps are sure to take her further up the party ranks yet.