Correspondence exchanged between the Queen and her representative in Australia in the lead up to the country’s only dismissal of a prime minister are to be released next week.

The letters, deemed “personal and confidential correspondence”, were deposited into the National Archives of Australia and were intended to remain private until at least December 2027.

But in May the Australian High Court overturned an earlier decision relating to the cache of letters and said the country’s National Archives should reconsider the request of historian Professor Jenny Hocking to access the documents.

Historians believe the documents will shed light on then governor-general Sir John Kerr’s decision to dismiss the then Labour prime minister Gough Whitlam in 1975, and replace him with opposition leader Malcolm Fraser, one of the most controversial moments in the country’s political history.

National Archives director-general David Fricker said all the letters will be released without exemption next Tuesday.

He said: “In line with the High Court ruling of May 29, the National Archives has examined the records for public release under the provisions of the Archives Act 1983 and I have determined all items will be released in full.”

In an event which has since been referred to as The Dismissal, Mr Whitlam was removed from office by Sir John after the Labour leader failed to pass a budget and then opted not to resign or call an election.

The newly sacked Mr Whitlam famously said on the steps of Parliament House in Canberra: “Well may we say ‘God save the Queen’ – because nothing will save the governor-general.”

Sir John cut his five-year term as governor-general short and resigned in December 1977 and eventually moved to London.

The records which will be released cover the period of Sir John’s term in office, 1974–77.

There are six files, which include more than 1,000 pages.

There are 212 letters, many with attachments such as newspaper clippings, reports, and copies of letters related to meetings and events attended by Sir John during his tenure as governor-general.