On the face of it, there is no smoking gun for those suspecting a dark conspiracy involving the Queen and the British Establishment to sack a democratically elected Labor prime minister of independent Australia.
On the face of it, the Queen stayed out of the decision itself.
But smoking guns are sometimes carefully hidden and there is a forest of paper yet to go through, paper from another era, all immaculately typed, no doubt not by the writers.
The letters do give a delicious flavour of the way the upper crust of the Australian and British public service talked to each other - "clubby" would be the word.
You imagine they knew each other and might have enjoyed a G and T together at the Carlton or Garrick in London or perhaps the Commonwealth Club in Canberra. And definitely at Lords or the Sydney Cricket Ground.
This is a genteel shared world of college and club and common values (by which I do not mean the values of the common people).
Common values like the lore of cricket.
Here's Sir Martin Charteris, The Queen's Private Secretary, writing to His Excellency, the Governor-General of Australia on October 8, 1975: "From your point of view, this would have been a real bouncer and not at all easy to play."
They are discussing scenarios - what would the constitutional position be if this were to happen or that? What might you do if so and so did that? It is a discussion involving lots of shoulds and woulds and coulds, all couched in that immaculate public (civil) service way made familiar in the Yes, Minister series. It really is the Queen's English.
The Queen was clearly kept well informed and if she didn't talk to the GG in Government House herself, then her son did.
There is an intriguing line in another letter to the governor-general from Sir Martin (or, to give him his full title as written in the letter: Lieutenant Colonel the Right Honourable Sir Martin Charteris, K.C.B., K.C.V.O., O.B.E., Private Secretary to The Queen).
He wrote from Balmoral, the Queen's autumn residence in Scotland, on October 2, 1975. Gough Whitlam was dismissed just over a month later and you feel the concern building in the correspondence.
"Prince Charles told me a good deal of his conversation with you [Sir John] and in particular that you had spoken of the possibility of the Prime Minister advising the Queen to terminate your commission with the object, presumably, of replacing you with someone more amenable to his wishes.
"If such an approach was made you may be sure that The Queen would take most unkindly to it. There would be considerable comings and goings, but I think it is right that I should make the point that at the end of the road, The Queen as a Constitutional Sovereign, would have no option but to follow the advice of her Prime Minister."
The implication of the letter is that if Mr Whitlam had asked the Queen (or The Queen, as the letters have it) to sack Sir John, she would have felt she had to do it, though she "would take unkindly to it".
That would have caused a real constitutional crisis with a scenario of Mr Whitlam asking the Queen to sack Sir John who was trying to sack Mr Whitlam.
It would have brought the Queen right into the middle, deciding between the Governor-General and the Prime Minister.
One way or another, this crisis was not going to be defused.
The letter ends: "Let us hope none of these unpleasant possibilities come to pass."
But "unpleasant possibilities" did come to pass.