The Queen would not support Prince Charles becoming governor-general of Australia until he had a "settled married life", the Palace Letters reveal.
"No one will know better than you how important it is for a Governor-General to have a lady by his side for the performance of his duties," the Queen's secretary, Martin Charteris, wrote to then governor-general Sir John Kerr, as the turmoil from the dismissal played out through 1976.
"The prospect, therefore, of the Prince of Wales becoming governor-general of Australia must remain in the unforeseeable future."
Prince Charles married Diana five years later, in 1981.
Eighteen months earlier, Prince Charles's attempts to buy property in NSW were also thwarted by the palace, despite efforts in Australia to help the prince with his plan.
Ahead of a visit to Australia by Prince Charles in October 1974, Sir Martin wrote to Sir John about Prince Charles's desire to buy a property.
"The public in this country would misunderstand a decision by The Prince of Wales to buy a property at a time of great economic difficulty for the United Kingdom and when housing is one of the worst problems which faces ordinary people," he wrote.
"In modern times it is never 'a good moment' for The Royal Family to spend money, but I think it fair to say that the present could hardly be a worse moment."
Prince Charles would "decide not to do anything at the present time about a property, but to keep his options as open as possible for the future".
But it seemed the young prince, then only in his 20s, had other ideas.
Sir John wrote to the palace on November 8, saying that Prince Charles had told him about "the attitude in the palace" to him buying land here, but after visiting the property had become "very anxious to try to explore alternative possibilities to enable something to be done before Christmas".
He organised a meeting with then prime minister Gough Whitlam who said the government couldn't help him financially, and so, "it seemed to be that the only way to produce a possible new situation might be if the whole scheme could be financed by loans negotiated in Australia", Sir John wrote.
"The Prince asked me to explore the possibility of this."
The high interest rates, though, appeared to put paid to that idea, with Sir John consulting "the English Dalgety's organization" and coming to the conclusion there was little difference between incurring a high debt here or simply sending money here.
Dalgety's though, "suggested the alternative scheme which you know about", which he passed on to the prince, who went to London, and "in due course told me the result."
This alternative scheme, which got short shrift in London, remains unexplained.
Sir John told the palace he hoped he hadn't "created problems in London" by trying to help the prince, but it had seemed impossible not to look at the possibilities "having regard to the Prince's eagerness" .
Sir Martin replied that "it is the greatest pity that it does not seem practicable for this project to come to fruition at the present."