Will Royal Whitlam letters get early release?

The 1975 dismissal of the Whitlam Government remains the most controversial, divisive event in our political history, and today another piece of the puzzle is under scrutiny in the Federal Court.

At the crux of the case are letters written between then Governor General Sir John Kerr, the Queen, her private secretary and Prince Charles in the weeks leading up to The Dismissal.

They are currently held in the National Archives of Australia, embargoed until at least 2027, at which time the Queen has final veto over their release.

Monash University academic and Whitlam's autobiographer Jennifer Hocking says the letters are documents of historical significance and should be made public.

But the National Archives claims the letters are in fact personal correspondence rather than official Commonwealth documents.

Hocking has plenty of big players supporting her case.

Earlier this year Prime Minister Malcolm Turnbull promised to ask the Queen to release the letters, but hasn't done so.

Her team of lawyers - all working pro bono - is led by Anthony Whitlam QC, the son of Gough and Margaret Whitlam.

The hearing continues in the Federal Court.