A decade since finding them in the archive, historian Jenny Hocking hopes to finally lift the lid next week on a box of letters between the Queen and the governor-general who dismissed Prime Minister Gough Whitlam.
The High Court has ruled the 211 letters should be accessible to the public and ordered the National Archives to reassess Professor Hocking's request to read them.
The judgment handed down on Friday comes after a four-year legal battle and a decade since Prof Hocking first sought access.
She says the archives must now release them immediately.
"I would anticipate that the archives is more than ready to have those documents available for me ... and I'll be able to sit down and start going through them," she told reporters in Melbourne.
"I would be horrified if they did (deny access) given the four-year legal case.
"Unless it has the Queen's medical details in it, you would expect them to be released."
Archives director David Fricker said on Friday afternoon staff had begun assessing whether there was any information in the letters that should still be withheld.
It has up to 90 business days to do so.
The National Archives of Australia and the Federal Court had deemed the so-called palace letters between Buckingham Palace and Sir John Kerr about the time of the 1975 dismissal as personal communications.
That meant they couldn't be released until 2027, and only then with the permission of the Queen.
But a majority of the High Court's full bench has ruled they are in fact Commonwealth property.
"A 'Commonwealth record' within the care of the archives must be made available for public access once the record is within the 'open access period'," the judgement from Chief Justice Susan Kiefel and Justices Virginia Bell, Stephen Gageler and Patrick Keane says.
In the case of the letters, that period is 31 years after creation, meaning they should have become public in 2006.
Justice Geoffrey Nettle made a dissenting judgment, saying the letters should not be deemed Commonwealth property simply because Sir John held public office.
Prof Hocking said the ruling could have implications for other correspondence between the Queen and governors held in state archives.
It has been hailed by the Australian Republican Movement as a win for Australian sovereignty.
"These letters provide a crucial historical context around one of the most destabilising and controversial chapters in Australian political history," chair Peter FitzSimons said.
"The Palace has claimed it had no involvement in the (dismissal) decision. This will put that to the test."
Labor also welcomed the decision, saying Australians deserved to know the full history, and former prime minister Malcolm Turnbull called for the letters to be released as soon as possible.
Australian Associated Press