Newly-released correspondence has revealed Her Majesty was not informed of her representative to Australia’s decision to dismiss then-prime minister Gough Whitlam in 1975 and replace him with opposition leader Malcolm Fraser.

Here, the PA news agency looks at some of the key questions surrounding the release of the letters.

– What do the letters say?

The biggest revelation from the correspondence is that then governor-general to Australia did not give Her Majesty advance notice of his decision to remove Mr Whitlam.

In one letter to the Queen’s then-private secretary Sir Martin Charteris, Sir John wrote: “I should say I decided to take the step I took without informing the palace in advance because, under the Constitution, the responsibility is mine, and I was of the opinion it was better for Her Majesty not to know in advance, though it is of course my duty to tell her immediately.”

Sir Martin responded by informing the governor-general the Queen had read “your statement with close attention” and he considered Sir John’s actions “cannot easily be challenged from a constitutional point of view however much the politicians will, of course, rage”.

– Why are they significant?

The letters are important because they add detail to one of the most pivotal moments in Australia’s political history.

The fall of Mr Whitlam’s Labour government is the only time in the country’s history a democratically elected federal government was dismissed on the British monarch’s authority.

The event also raised questions over Australia’s political independence from Britain.

– Why was Mr Whitlam removed from office?

Mr Whitlam was dismissed as prime minister on November 11, 1975.

Amid a troubled economy and turbulent political situation, a constitutional crisis was reached when the Australian senate refused to pass a national budget until an election was called.

Mr Whitlam, who held a majority in the House of Representatives, refused.

Following three weeks of a parliamentary stalemate, Sir John ultimately made the decision to sack Mr Whitlam and put Mr Fraser’s opposition Liberal Party in power as a caretaker government – until they were elected to the position just over a month later.

The correspondence has also revealed that Sir John acted out of fear of his own dismissal, and the position that would put the Queen in.

Sir John wrote: “If, in the period of say 24 hours, during which he [Mr Whitlam] was considering his position, he advised the Queen in the strongest of terms that I should be immediately dismissed, the position would then have been that either I would, in fact, be trying to dismiss him while he was trying to dismiss me — an impossible position for the Queen.”

– Why was the correspondence not released earlier?

Under normal circumstances, government documents held in the National Archives of Australia become public 30 years after being written.

However the Archives had declared the letters “personal” and not state records, meaning they were to remain private until at least December 2027 – though the private secretaries of both the sovereign and the governor-general in 2027 could still have vetoed their release indefinitely.

– Why were the letters released?

The correspondence was finally released following a legal battle launched in 2016 by historian Jenny Hocking, who had argued the correspondence should be released regardless of the Queen’s wishes because Australians have a right to know their own history.

In May, the Australian High Court overturned an earlier decision relating to the cache of letters and ruled the Archives should reconsider Ms Hocking’s request to make the documents public.