PROF. JENNY HOCKING, POLITICAL HISTORIAN: The history of the Whitlam government itself has been so clouded by secrecy, misunderstanding and in some cases, outright deception about what actually happened.

ASHLYNNE MCGHEE, REPORTER: Melbourne historian, Jenny Hocking, has spent nearly a decade fighting our national archive to release letters the Queen wants to keep secret.

PROF. ANNE TWOMEY, UNIVERSITY OF SYDNEY: This is a really important case because it is about Australia being able to keep control over its own history.

(Extract from archival footage)

GOUGH WHITLAM: Well may we say God save the Queen because nothing will save the Governor-General.

(End of extract)

JENNY HOCKING: Well, the palace has denied us access to these letters and I think obviously the question arises, why?

ASHLYNNE MCGHEE: In November 1975, the nation was in a constitutional crisis.

(Extract from archival footage)

DAVID SMITH, GOVERNOR-GENERAL'S OFFICIAL SECRETARY: Proclamation by His Excellency, the Governor-General of Australia.

(End of extract)

ASHLYNNE MCGHEE: The Governor-General, Sir John Kerr, kept the Queen updated in what's known as the 'palace letters'.

JENNY HOCKING: We know that Kerr was writing to the Queen frequently, that he was sending several letters in a single day at times.

But we also know he might attach somebody else's letters to him, certainly newspaper reports of the crisis that was unfolding in Australia at the time, opinions on that, other people's writings about that.

ASHLYNNE MCGHEE: On the 11th of November, John Kerr dismissed Whitlam's government.

(Archival footage)

JENNY HOCKING: So it will be very important to know what version of that particular history Kerr was sending on to the Queen.

ASHLYNNE MCGHEE: The palace letters include about 50 to 60 pieces of correspondence sent between John Kerr and the palace during his tenure as Governor-General.

They are sealed in a secret file held at the National Archives.

But Jenny Hocking has had a small victory - the archives has released some letters from 1978.

She's given 7.30 the first look.

JENNY HOCKING: These letters are letters that date from after Kerr's period as Governor-General.

It shows the palace and Kerr coming to an arrangement to omit key material involving the palace from his memoirs.

I call that a royal whitewash of history and it's absolutely shocking that the outcome of that is a distorted version of history that, in effect, has been vetted by the palace.

ASHLYNNE MCGHEE: Buckingham Palace is intent on continuing to vet which documents are released.

By law, all Commonwealth documents held by the National Archives, should be released after 31 years so in the case of the Kerr papers, 2005 onwards.

But the archives say these are private letters and Buckingham Palace has ordered they be sealed for 50 years and that even then in 2025, the palace still has the final say on whether they see the light of day.

Anne Twomey is an authority on constitutional law.

ANNE TWOMEY: Without access to these documents conspiracy theories flourish because people can always say, "Oh well, the Queen was conspiring with the Governor-General to dismiss the Prime Minister," or any of those sorts of things because of the fact that the secrecy is keeping this information out of Australian hands.

ASHLYNNE MCGHEE: She's a close observer of the palace letters case.

ANNE TWOMEY: The central question that the court is looking at is whether the documents belong to the Commonwealth or whether they're private and personal letters that belong to Sir John Kerr?

It's actually quite a hard question to answer.

Most of us would think that if you're writing that kind of an official letter as part of your job, then it would be a letter that belongs to your employer which is essentially the Commonwealth.

ASHLYNNE MCGHEE: Monarchist, Phillip Benwell, is certain they're private.

PHILIP BENWELL, AUST. MONARCHIST LEAGUE: We're now looking at going through communications between the Queen and her representative, the Governor-General, and vice versa, just for the sake of trying to find some snit bit of information that can be sensationalised.

ASHLYNNE MCGHEE: The National Archives declined to comment.

Jenny Hocking is flying to Canberra to make her case before the full bench of the High Court on Tuesday.

It's entirely crowd funded and she has a final message for one of the most powerful institutions in the world.

JENNY HOCKING: I would say open your letters and open your archives and let Australians see that.

If we have to have secrecy over royal activities, then it suggests that those royal activities are hiding something that they simply don't want the Australian people to know and I think, for an autonomous nation, that is simply unacceptable.