For a key moment in one of the biggest national security breaches in the nation's history, it was an unlikely setting.

At a house outside Canberra, the flies were buzzing, the dogs were hanging around and a serious amount of steak and sausages was sizzling away on the stove.

Waiting for their mountains of meat to cook, two men sat at a table drinking beer and chin-wagging about the affairs of the nation.

One was journalist Michael McKinnon, the ABC's Freedom of Information editor. The other was a bushie who had lived in and travelled to different parts of the country.

The two men had struck up an instant rapport — so much so that when the meat was put on the table McKinnon asked: "Don't you have any vegetables!"

"No vegies at the moment," the man replied. "The wife's away right now and she's the one who buys vegies. I can cook you some onions if you like?"

That night would prove a decisive moment in one of the most extraordinary episodes in Australia's national security history, with the release of hundreds of highly-classified documents.

This week, the ABC agreed to return to the Government the hundreds of documents which had ended up in the bushie's shed.

The return of the documents came after an agreement which protected the bushie.

Two cabinets for $10 each

The story begins at a second-hand auction house in Canberra in the middle of last year.

The man cooking the steak and sausages had gone to Canberra to buy some filing cabinets — he knew that you could always get good furniture at the shops around the capital which sold used government supplies.

He'd taken a ute so that he could buy some filing cabinets. He'd bought several — all empty — when the man who owned the shop told him there were a couple he could have at bargain-basement price.

"Those two over there you can have for $10 each," he told the man.

"We haven't got keys for them — but you might have trouble getting them into the ute because they're pretty heavy."

Pretty heavy, indeed — heavy with national security secrets.

The filing cabinets had been in the Department of Prime Minister and Cabinet and contained documents from the bureaucracy which detailed cabinet deliberations for every prime minister between John Howard and Tony Abbott.

Back home, the man put them in his shed. And so, the filing cabinets sat week after week, month after month — some of the most sensitive material relating to security — sitting in a musty shed outside Canberra.

Meeting Michael McKinnon

Finally, the man decided he'd organise his new cabinets — he drilled holes in the locks of the two that had no keys.

He was stunned by what he found. He sat in his shed reading first-hand accounts of the Howard, Rudd, Gillard and Abbott governments.

"He's a completely apolitical man," McKinnon said.

"He thinks that all politicians need to lift their game, but as he read some of the documents showing that some politicians had been saying one thing and doing another he decided the public had a right to know all of this stuff."

But what was the next step? He wanted some of the material in the public domain, so began researching journalists.

He discovered that someone called Michael McKinnon had been to courts and tribunals more than 100 times fighting for the release of documents.

McKinnon had been as far as the High Court fighting for documents. He'd been appointed the nation's first FOI editor — by The Australian — and was clearly committed to documents being published rather than suppressed.

McKinnon would turn out to be a perfect choice — before university he'd worked in the bush, where he would round up cattle on horseback for a year.

He knew how to talk to someone from the bush, but he also knew his way around the capital — if the public service had such a thing as royalty, McKinnon's family would be in it.

Sorry, this video has expired ASIO officers deliver safes for the ABC to store The Cabinet Files in. (ABC News: Dan Conifer)

'This one was a cracker'

McKinnon was born and raised in Canberra — his father, W.A. (Bill) McKinnon was secretary of the Department of Immigration in the 1980s.

He was also head of the Industries Assistance Commission and High Commissioner to New Zealand. His grandfather was Alan McKinnon, the Commonwealth statistician in the 1930s.

His brother is Allan McKinnon, a deputy secretary of the Department of Prime Minister and Cabinet who is currently in charge of national security for the Federal Government.

His other brother, John, is deputy director of the Australian War Graves commission and his sister, Margaret, is a senior executive in the Department of Human Services.

"I'd be embarrassed if I had to find a story by talking to my family," McKinnon said. "They'd be embarrassed, I'd be embarrassed."

The man rang McKinnon, and they had their first phone call. McKinnon listened to an extraordinary tale, and at the end of that phone call said to the man: "Having dealt with thousands of documents, my first advice to you is seek your own legal counsel. You need to understand exactly what this might mean for you if we go ahead with this."

Several weeks later, the man called McKinnon again.

"I've got my legal advice and gone through some of the documents again — I want you to come to see me," he said.

McKinnon then telephoned his boss, Craig McMurtrie, the ABC's deputy director of news.

"From that first conversation we were extremely conscious of the national security implications and continued to be mindful of that through the editorial process," McMurtrie said.

"But our job as journalists is to report good stories and serve the public, and this one was a cracker."

The files were later placed in a safe provided by ASIO, which the ABC could access. ( ABC News: Danielle Bonica )

'This is the real deal'

McMurtrie sent McKinnon to Canberra. McKinnon would stay for the night at the man's house. They sat up late drinking beer — the night of the steak and sausages.

"I remember sitting there with the fire going at night and looking at these documents and thinking this is the real deal," McKinnon said.

"I was stunned," he said, when asked his reaction when he saw the documents.

"As a 19-year-old I had worked in the Department of Prime Minister and Cabinet in the registry — the dead dull administrative unit that handles all the top secret files.

"I never read any of them because it wasn't my job, but when I saw all these I realised this was an extraordinary cache of documents.

"I've seen thousands of government documents in my time, but here I am, sitting in the bush with the flies buzzing in a house he's built himself with a quintessential Aussie bush bloke and I'm thinking to myself this is real.

"Reading those documents that night, it was clear to me there was a public interest in the public knowing this material."

McKinnon called his colleague Ashlynne McGhee in the ABC's Canberra bureau.

"I'd worked with Ash before and she's a very, very good journo. I knew she'd work hard and that we could trust each other implicitly," McKinnon said.

Like the man in the shed, McGhee would have a rare glimpse into the nation's deepest secrets.

"This week Ash worked across platforms every day — I could not do that. I was in awe of what she did," McKinnon said.

Thousands of pages of documents, some marked "top secret", were obtained in the sold-off filing cabinets. ( ABC News: Melissa Clarke )

The three options

McGhee still remembers the first phone call from McKinnon about this group of documents.

"Michael told me that a guy went to an ex-government auction and picked up filing cabinets and inside there were Cabinet files," she said.

"I asked Michael to repeat what he was saying — he said it again and it all started to kick in. Everything started to kick in then but it was months before we got the documents.

"As the months went by and I heard nothing I thought that's a great story we're never going to be able tell. It wasn't until late last year when Michael called me and said, 'Good to go! We've got 'em!'

"I turned to Bradders (Gillian Bradford, the ABC's Canberra bureau chief) and said, 'I've got to get out of here'. I went and picked up the documents in a big heavy dusty box.

"When I opened it, the papers were out of order and stuff [was] everywhere and I realised the enormity of what this actually was.

"My reaction was the same as everyone else when we broke the story of the two filing cabinets on Wednesday, except I had a few months to get used to it."

McGhee photocopied the documents, sending one set to McKinnon in Brisbane. They then indexed them, and would go through every single one of the documents.

Once they had authenticated the documents and ordered them, the ABC had three options: the first was to "do a WikiLeaks". The second option was to hand all the material to the police, and the third was to do journalism — go through the documents and examine whether there were stories of public interest.

Everyone involved in the process at the ABC agreed that any documents which could endanger public safety or national security if published would not be published.

Instead, we focused on stories which, while embarrassing to certain political figures such as Kevin Rudd, Penny Wong, Scott Morrison and Tony Abbott, were clearly not of any security threat.

Sorry, this video has expired ASIO takes custody of secret cabinet documents, obtained by the ABC

'We decided to do the journalism option'

The "WikiLeaks option" would have been to put all of the documents online — the publish-and-be-damned model. This option was opposed from the start by the Canberra bureau and, later, ABC executives involved in the decision — the Director of News, Gaven Morris, Craig McMurtrie and myself.

"We decided to do the journalism option," Morris said.

"To me the first two options weren't journalism — we decided that we would do stories from the documents which were in the public interest and which did not damage national security in any way."

Like Morris, I too was opposed to the WikiLeaks option — I'd been appalled when WikiLeaks in 2016 did one of their "dumps" of thousands of documents which revealed information which in my view had no public interest.

As Associated Press reported at the time under the headline, 'Private lives are collateral damage in WikiLeaks' document dumps', WikiLeaks had published medical files belonging to scores of ordinary citizens while many hundreds more had had sensitive family, financial or identity records posted to the web.

AP reported: "In two particularly egregious cases, WikiLeaks named teenage rape victims. In a third case, the site published the name of a Saudi citizen arrested for being gay, an extraordinary move given that homosexuality is punishable by death in the ultraconservative Muslim kingdom."

Once the decision had been taken to publish only documents of public interest rather than those that included sensitive operational matters, the roll-out was planned.

Journalists contacted key people named in the documents, so they could respond to suggestions made in the documents or put them into perspective.

And so, last Monday, the first of the Cabinet Files was published.

ASIO officers retrieved papers in Canberra, Melbourne and Brisbane late on Thursday evening. ( ABC News: Dan Conifer )

'I think people have a right to know'

By Wednesday, the ABC had published all the documents that it deemed of public interest.

"We could have told hundreds of stories over weeks or months," Morris said.

"Instead, we chose to be selective and responsible in what we broadcast."

Meanwhile, ASIO and other government agencies became alarmed that the documents which the ABC was not prepared to publish may fall into the wrong hands — they sent safes with combinations to the ABC's office as negotiations began to get the documents back.

After a day of negotiation — the ABC's main concern was the protection of the source — the documents were returned to the Commonwealth Government.

Ironically, the Cabinet Files publication has come as Federal Parliament is set to debate a new espionage law.

While the law purports to be targeting foreign agents operating in Australia, it will potentially criminalise some forms of investigative journalism as early as the research phase.

It would be a potential offence to "deal with" confidential information. Should a federal police officer or public servant want to speak to a journalist about possible corrupt behaviour, the very act of them speaking to a journalist could make them, and the journalist, liable for up to 20 years' jail.

Every media organisation I have worked for — The Australian, The Sydney Morning Herald, the Nine Network, The Bulletin and now the ABC — have treated confidential material carefully.

There are already strict laws of defamation, contempt and confidentiality which media organisations work within.

While the media has no shortage of critics — often justifiably — one aspect where the media in Australia does have a good record is in the handling of confidential documents.

The ABC displayed that this week — it published stories which helped the public better understand its political process and then returned the documents to ensure that any operational matters regarding Australia's national security system would not be revealed.

The Australian public is now better informed than it was this time last week.

As the bushie had said that night last year over steak and sausages: "I think people have a right to know what's going on in their country."