When Hedley Thomas gets his teeth into a story you can be sure he’ll shake it until it becomes a national scandal.

“Hedley is an attack dog — in a good way and a bad way,” says a former senior colleague at The Australian. “When Hedley gets an assignment he will never let go of it.”

Over the past two years, Thomas’ reporting has helped force the Victorian police commissioner out of office, led to the re-opening of the Queensland flood inquiry and forced Julia Gillard to publicly address her former relationship with a union conman. Yet he’s an enigmatic, divisive, at times abrasive figure.

“Hedley is the best journalist in the country,” says Australian Women’s Weekly editor and former Australian colleague Helen McCabe — a judgment supported by his five Walkley wins and pair of nominations for this year’s awards.

Others are not so glowing. In 2010 media commentator Margaret Simons described The Oz‘s reporting on Victorian police issues — led by Thomas — as “something warped and dangerous in journalism”. Mark Latham slammed his reporting on Gillard’s history as a Slater & Gordon lawyer as the “politics of smear”.

His strident opinion article excoriating reporters — including Michelle Grattan and Fran Kelly — for their coverage of the latter story raised the hackles of many hacks. “I’m glad I wrote it — in fact I probably should have gone harder,” Thomas says of the piece, headlined “Media’s shameful silence”.

In a lengthy phone interview, Thomas, who works in The Oz‘s Brisbane bureau, speaks slowly and quietly — never raising his voice. But his language is forceful, muscular, peppered with four-letter words: like the paper he works for, he’s an “elbows out” personality not short of self-confidence.

“I don’t believe the Canberra parliamentary press gallery is as fiercely independent as we should hope for,” he says. “There’s an undeniable political bias among some of the commentators that infects their coverage. I don’t have that bias.”

In her marathon press conference on her Slater & Gordon days, Gillard conflated The Australian‘s reporting with rumour-mongering by “misogynists and nutjobs” on the internet. But Thomas’ reports were based on fresh interviews and documents, not smears: the transcript of Gillard’s “slush fund” exit interview was a brilliant “get” any news outlet would have been keen to publish. As for the argument his reporting was part of a News Limited/Coalition conspiracy, The Age’s extensive follow-up reports show that’s not true.

Thomas, unsurprisingly, doesn’t agree with the press gallery consensus that it’s time to leave Gillard’s past in the past.

“It was bizarre that the Prime Minister could say, ‘I’m going to answer your questions now and I’m never going to deal with this again’,” he says. “Well I’m sorry: you’re the prime minister of Australia and these are questions about your integrity, your ethics and a very serious fraud that was facilitated with a slush fund that you helped establish for your then boyfriend. These are matters that don’t just go away because you say you won’t take any more questions on this.”

There’s no evidence, however, the general public is half as scandalised by what Gillard got up to as a lawyer 17 years ago as Thomas is. In fact, the Prime Minister’s poll ratings have improved since he took on the issue.

“I don’t understand, in journalistic terms, why so much effort and so many thousands of words were dedicated to that story,” says former Media Watch host David Marr. “Until you can tie Gillard to the theft, or facilitating the theft, she’s clean. And I don’t see anything in the stories that tied her to the theft.”

But there’s no doubting the real-world impact of Thomas’ reporting on Wivenhoe Dam. The Queensland Floods Commission of Inquiry was recalled in January following his stories, based on internal emails and technical reports, alleging the dam was mismanaged and that a cover-up had taken place. In its final report, the commission found the flood manual had been breached, a conclusion that will buttress a massive class action suit.

In August, the Crime and Misconduct Commission found no evidence of criminal or official misconduct against the three engineers. An independent review last month concluded the engineers’ decisions were prudent and that alternative operations would not have made a significant difference to the flood’s magnitude — findings at odds with The Oz‘s reporting.

Thomas maintains: “The work we did in relation to exposing the Wivenhoe dam operation and what the inquiry had missed is some of the work I’m most proud of and I’m grateful to the newspaper for backing me.”

Thomas began his career at the Gold Coast Bulletin in the dying days of the Joh Bjelke-Petersen regime, an experience that convinced him the journalist’s job is to get off the drip, question official narratives and rail against abuses of power. Stints at The South China Morning Post and The Courier-Mail, where he brought “Dr Death” Jayant Patel to national attention, then followed.

In 2007, he won a Gold Walkley for exposing the dodgy evidence against accused terrorist Mohamed Haneef — “one of of the crucial stories of the decade”, according to Marr.  Exhausted and convinced his career had peaked, he left The Australian to do PR work for a Queensland gas company. “It was probably a bit of a cop-out,” he reflects.

Within two years he was back at The Oz, filing stories highly critical of Victoria’s Office of Police Integrity. This work was criticised on many grounds: he was too close to disgruntled police sources, he was rehashing old claims, his stories were tainted by an ongoing stoush between his paper and the OPI. The last claim, he says, is “complete bullshit”.

“I don’t write stories I don’t believe in.”

In many ways, however, he feeds off such criticism: Hedley’s happiest when it’s him against the world. “I would prefer to be an outsider than an insider,” he says. “I would prefer to be a contrarian. I never want to be part of the herd.”