The then leader of the opposition, Dr Bert Evatt, rose in the House of Representatives in October, 1955, to try to discredit the Royal Commission into Espionage, launched by the Menzies government, after the defection of Soviet spy, Vladimir Petrov, and his wife.

The Labor Party at the time was in disarray over both the issue of communism and the increasingly erratic leadership of Evatt – but if there was a single act on the part of Evatt to destroy any lingering credibility he had managed to retain, then this was it.

He had, he told the House, written to the Soviet foreign minister, Vyacheslav Molotov, asking if allegations of Soviet espionage in Australia were true. Molotov duly replied, denying the allegations.

For a moment the House sat in stunned silence as Evatt paused. Then the House erupted in uproar, most of it laughter from both sides.

Evatt, although shaken, continued amid a barrage of catcalls and interjections: “Honourable members may laugh, but they have to face some facts to-night. They will not put me off by their organised opposition. They have to listen to this because this is the truth of the affair. The letter to which I have referred informed me that the documents given to the Australian authorities by Petrov” — and here Evatt quoted from the letter — “can only be, as it had been made clear at that time and as it was confirmed later, falsifications fabricated on the instructions of persons interested in the deterioration of the Soviet-Australian relations and in discrediting their political opponents.”

Evatt said he attached “grave importance to this letter which shows clearly that the Soviet government denies the authenticity of the Petrov documents. It seems to me that in these circumstances the matter cannot be left where it is, and that, if possible, some form of international commission should be established by agreement with the Union of Soviet Socialist Republics to settle the dispute once and for all. The Soviet Union was not represented at the hearing. It will be in a position to prove clearly, definitely and unequivocally, that the letters are fabricated.”

Members on both sides were incredulous: what he was doing here was accepting the word of a foreign government over that of the Australian government and ASIO. Evatt’s leadership never recovered from this, and it provided his critics, many of them in his own party, with evidence of his deteriorating state of mind.

The announcement by prime minister Robert Menzies of the Petrov defection and the subsequent Royal Commission came on the eve of the 1954 election. Evatt's failure to win the election led him to blame the Catholic-dominated anti-communist “Groupers” in the party for sabotaging his campaign. Further, he believed Menzies had conspired with the security services to bring about Petrov’s defection with the specific purpose of discrediting him. Documents shown to the commission were alleged to provide evidence of an extensive Soviet spy ring in Australia, and named, among others, two of Evatt's staff members.

Evatt’s decision to write to Molotov was his alone, and his staff had sought to dissuade him. One staffer, Allan Dalziel, later wrote how Evatt had called him at home and dictated a cable he wanted sent to Moscow.

Dalziel did not send it. He understood immediately the implications if it was revealed Evatt had been in touch with Moscow. “I then put the draft in my desk drawer and locked it up,” he wrote. But Evatt found a way around him, writing a letter himself and having it sent through the Swedish embassy in Canberra.

The final report of the Royal Commission was released on September 14, 1955. It concluded that the Petrov documents were genuine and that the Petrovs were “witnesses of truth.” However, no prosecutions were recommended as a result of the inquiry.

It was the release of the final report that sparked Evatt’s performance in the House five days later.

Evatt never recovered from this, and his actions undoubtedly exacerbated growing tensions within the party that led to a split, loss of government in Victoria and Queensland as a result and a further 17 years in the political wilderness federally.

It remains to be seen whether Donald Trump’s preference for Moscow’s word over that of his own intelligence agencies inflicts similar political wounds to those self-inflicted by Evatt.

Dr Norman Abjorensen is a Canberra political historian