In Launceston to speak about his newest book, A Memoir, O’Brien spoke about the political moments he had covered that defined Tasmania as a state, but also those that stuck in his mind.

He listed the ongoing wood chip debate, the rise of the Greens and the 1975 Tasman Bridge collapse as highlights.

“I can remember coming down here to cover the inquiry into the bridge over The Derwent, when the ship went into it and the bridge collapsed [for This Day Tonight]. And I then came down from Melbourne to cover the findings when they were released,” he said.

“I’ve introduced a lot of stories from Tasmania over the years and interviewed a lot of people – various premiers and so on – but it is constantly challenged in terms of its economy. It’s wonderful to see the impact of Mona as a huge drawcard for tourism.”

The biggest Tasmanian story, and one which Mr O’Brien spends a lot of time reflecting on in his memoir, is the Port Arthur Massacre.

It was significant for him for personally, as well as professionally.

Tasmanian correspondent Judy Tierney “was terribly affected by it, but reported it faithfully” and Lateline journalist Eleanor Hall’s sister Zoe and Zoe’s partner died during the event.

“They were just shot; promising lives ended so randomly,” he said.

Recalling how the massacre was reported, O’Brien spoke about a Victorian nurse named Lyn (the ABC did not reveal her surname) who found herself caught up in the event, but helped the victims “not knowing whether the gunman was going to be coming around the corner at any time”.

“She gave us a truly remarkable, unique interview, that was so compelling I felt the hair on the back of my neck rising when I read back through the transcript for the book,” he said.

“I will never forget that massacre, as I’m sure many people won’t forget that massacre, but as a program we threw everything at it to do it justice.”

It was this event that became a defining moment for Prime Minister John Howard because it was his first major challenge – and triumph – as he moved swiftly to change Australia’s gun laws in the aftermath of the massacre.

“He had barely become Prime Minister and it was, in many ways, probably his finest moment,” Mr O’Brien said.

“His leadership, at that point, was inspirational. I remember all those things. He got enormous resistance within elements of the National Party, and even some elements of his own party. He and Tim Fisher met that front on together.

“They went to Gympie, in Queensland, where an effigy of Tim Fisher was hanging from a rafter, where the crowd was extraordinarily angry, and they stared those people down. That took courage on John Howard’s part, and I think he deserves a huge tick for it,” he said.

Moving on to politics of another kind, O’Brien shared what it was like to work for an organisation that spent many years under pressure from the government of the day.

He was a journalist politicians wanted to “take down”, with O’Brien, and some of his ABC colleagues, even featuring on past managing director Jonathan Shier’s “hit list”.

Admitting to being “a bit bemused” by this, O’Brien said the environment simply inspired him to do his job better.

“I was told by a friend, who had heard from one of the shortlisted candidates for the managing director's job, that he had been shown a hit list and some of the names on that hit list were Barry Cassidy, Heather Ewart and myself, who were all at 7.30,” he said.

“We knew there was a game going on that might not be very pleasant, and we just girded our loins and got on with the job.”

Despite board appointments – including Donald McDonald and Michael Kroger, who were personal friends of John Howard and Peter Costello respectively – that put the ABC under further pressure, the national broadcaster survived.

“There was this lineup of people whose view of the ABC was wildly different to the ABC that we already had – an ABC that was massively liked and trusted and respected by the broad Australian populous. That, I suppose, was the thing that kept us going,” he said.

“I’d decided early on that the only response I could give that would make any sense was to walk the straight line, play a straight bat, do my job as professionally as I could and let my work speak for itself.

“At the end of the day Jonathan Shier was shown the door and we were still there. And eventually the government departed too.”

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