There's no return address or contact number. It's signed only "Norman".

Not the first tip-off the Newcastle Herald journalist ever received on a predator priest, but it's the letter McCarthy keeps coming back to.

"He was telling me about a school friend who'd been abused [in the 50s]," McCarthy says.

"His friend had died but his abuser Brother Leon was free. I've looked at that letter so many times over the years, the writing is shaky in places. There are so many like that. No addresses. They don't want compensation. They want someone to bear witness."

McCarthy's subsequent reporting on Brother Leon and others "looked after" by the Archdiocese would lay much of the road for the coming Royal Commission, which ran until 2017 and has helped reshape both church and state in Australia.

Now, Norman's letter is "on loan" as part of an exhibition unveiled at Old Parliament House on Thursday.

Sitting side by side with the now famous thank you letter Julia Gillard sent McCarthy in her final act as prime minister (along with the 19^th century printing press of Sir Henry Parkes), Norman's words offer perhaps a much-needed reminder: this is what can happen when the public trusts its media.

But in 2019, director at the Museum of Australian Democracy Daryl Karp admits trust of any kind is in short-supply.

As the media weathers a "perfect storm" of industry disruption, fake news and government overreach, Karp says its role in a healthy democracy is "fraying at the edges". A recent survey of more than 1000 Australians found about half of young people were getting their news from unverified sources - celebrities or their family.

While information might be more accessible than ever before, Karp says "truth decay" is now eating away at the rigour of public debate, with facts increasingly confused for opinion.

This week, as curators were putting the final touches on the exhibition, Australia's top media brass were arriving at the house just up the hill to lobby for a windback of almost two decades of "heavy-handed" national security laws affecting both journalists and whistleblowers.

The "Your Right to Know Campaign", which is supported by the publisher of both The Canberra Times and The Newcastle Herald, Australian Community Media, emerged after police raids on the ABC and a News Corp journalist earlier this year.

Journalist Hamish Macdonald says his colleagues at the ABC still face charges as the country grapples with the question: "Is journalism something you can go to jail for?".

While the current "culture of secrecy" hasn't come out of nowhere, Macdonald says it's shocking nonetheless to see it take root in a Western democracy like Australia.

He and McCarthy are among 12 prominent journalists now sharing the stories behind some of the nation's biggest moments as part of the exhibition.

Standing side by side in seven-foot tall immersive video displays, household names from Peter Greste to Adele Ferguson reveal the personal toll of their work - and why it matters to a democracy.

"It's been surprisingly emotional," Macdonald says.

Curator Holly Williams says that, while the media don't always get it right (there's a wing devoted to the Lindy Chamberlain saga sitting quietly off to one side), so many of the big changes that have transformed Australia began with a "tenacious journalist picking up a story".

Despite the often gloomy forecast for journalism, Macdonald sees bright spots too, as new platforms and technologies drive new kinds of engagement with audiences.

"When I started as journalist here in Canberra...at WIN TV, we had two-way radios in the car, we didn't have email addresses, we didn't even have internet on all the computers in the newsroom," he says. "We cut the stories on tape in the afternoon to get to air at six o'clock at night.

"Today that is revolutionised and there's things we've lost with change but there's all sorts of ways to deliver the news like we never could before."

Reflecting on her own near four-decade career ("I wasn't even supposed to be a journalist, I wanted to be a librarian"), McCarthy says the media has always been there for the community and will continue to keep watch.

"But we have as much to do as governments and other institutions to reclaim that trust...doing our work is part of it and being prepared to speak out now is part of it.

"Recent years really have sent a chilling effect.

"People find it so difficult to reach out, particularly if they're at the end of the line of a system that has smashed them...For there to be any [further] obstacle, we really do have to stand up to that."