Louise Tarrant is demurely-dressed and softly-spoken — an unlikely radical if ever there was one. Yet she, as much as anyone else, is redefining what it means to be a unionist in 21st century Australia.

Tarrant is the national secretary of United Voice, a left-wing union representing 120,000 workers in some of our most precarious and poorly-paid industries: childcare, aged care, cleaning, and hospitality.

Over the past two decades, she’s been the most influential local advocate of the so-called “organising model” — a controversial approach that repositions unions as grassroots campaigning machines, rather than bargaining outfits, and eschews militancy in favour of constructive relationships with employers.

She’s a philosopher, a persuader and a risk taker. Just look at her decision to ditch her union’s former name (the Liquor, Hospitality and Miscellaneous Workers Union). Or to launch The First Star, a Wotif-style website encouraging travellers to make bookings with ethical luxury hotels.

“She has left-field ideas, she challenges people, she tries different things,” says ACTU assistant secretary Tim Lyons. “She doesn’t have a huge public profile but she has an intellectual take on things that is compelling.”

Chris Walton, a former senior ACTU official, describes Tarrant as “the conscience of the Australian union movement and a real talent”.

But she has her critics, too. Some branch officials were angry she didn’t speak out against Julia Gillard’s pre-commitment pokies deal with Andrew Wilkie (United Voice represents workers in pubs, clubs and hotels). Traditionalists also see her tactics as too soft and fluffy.

“Louise Tarrant runs a cult, not a union,” remarks one union and ALP insider. “They’re all about organising members, not servicing them. A lot of people think they’ve drunk the Kool Aid.”

Tarrant laughs off the cult leader tag during an interview with The Power Index in her Sydney office. But she has a potent message for her doubters: resist change at your peril.

“Too much is happening around us for us just to restrict ourselves to the workplace,” she says. “We exist to make positive change in workers’ lives. That’s our benchmark and we’ve struggled in recent decades to deliver on that promise.”

The most recent example, of course, of a union spectacularly failing to deliver on its promise is the Health Services Union. And the excesses of the HSU are clearly on Tarrant’s mind during our interview.

“We’re not a big spending union, we’re a very lean organisation,” says the proud penny pincher, who shifted United Voice’s national office from the CBD to Redfern to save money.

When United Voice officials travel interstate, they’re also expected to catch public transport from the airport rather than taxis. “We’re really conscious that when we spend money, it’s out of a low income worker’s pocket,” she says.

Tarrant knows what it’s like to be poorly paid: she started out as a telephone operator at the Sydney GPO and became active in the telephonists’ union. Before joining the LHMU full-time in 1993, she worked as a consultant on union amalgamation campaigns and recruitment strategies.

Tarrant has drawn much inspiration over many years from United Voice’s US sister association: the Services Employees International Union (SEIU). More recently, she’s been taken by the Occupy movement’s ability to put equality at the heart of economic debate in America.

“In most of our areas it’s very difficult to bargain through traditional strategies,” she says.”We’ve got to change the economics of an industry to deliver something for workers.”

This approach has paid off spectacularly with Clean Start — a local version of the SEIU’s famous Justice for Janitors campaign. The seven-year-long crusade has achieved increased hours and pay rises of up to $200 a week for office cleaners through agreements with property owners, contractors and governments.

*Read the full profile at The Power Index