In April 1933, Sutch was one of four people including Morva Williams, his future wife, who were reported missing in the Tararua Range during an attempt to be the first to follow a particular route during the winter season.

The trip was scheduled to take two days, but they were delayed when two of the members were injured in a fall and all were forced to travel very slowly through some of the worst weather recorded, before finally making their way out more than two weeks later.

In 1933, following some teaching in Palmerston North Boys' High School, Sutch took up a position in the office of Gordon Coates, who was Minister of Finance.

[5] At the end of the war, he took up a position with the new United Nations Relief and Rehabilitation Administration (UNRRA), working in Sydney and then in London, covering war-devastated Europe.

As a result of this work, he was selected to head the New Zealand delegation to the United Nations, where he held positions with the Economic and Social Commission and UNICEF.

Prime Minister Walter Nash, who knew Sutch well, ignored the objections of the Security Service who thought an appointment was not worth compromising allegiance to the United States.

He concluded that pastoral exports by themselves would not generate enough foreign exchange to maintain full employment, and would continue to make the economy highly vulnerable to fluctuations in international conditions.

[7] Economist Brian Easton has argued that: "The events surrounding the trial overshadowed the significance of what went before, and have muted subsequent recognition of his intellectual contributions.

Sutch claimed his meetings with Soviet officials were after the Russian ostensibly approached him in his capacity as a stalwart of the NZ Friends of Israel, for information about who were the Zionists in New Zealand, and to discuss China.

Sutch began to suffer ill health at about the same time as he was arrested and died from liver cancer six months after the trial on 28 September 1975 at Wellington, shortly after holding his just-born first grandson, Piers.

On the other hand a Top Secret 1976 report by chief ombudsman Sir Guy Powles found that SIS actions had been unlawful when they burgled and bugged his office.

[11] In August 2014, the University of Cambridge released details from the KGB files from the Wellington Embassy that they held in archives that had been provided by Soviet defector Vasili Mitrokhin in 1992.

According to Phil Kitchen of The Dominion Post, "The documents don't name Sutch but the details clearly identify him and state he was recruited [by the KGB] in 1950."

[17] Sutch's daughter did not accept the evidence, stating: "It is well known that KGB agents in general were desperate to talk up any contacts they had because they were under pressure from their superiors".

His marriage to Morva was dissolved on 2 February 1944, and he married Shirley Hilda Stanley Smith (1916–2008), a lecturer and later a lawyer, in Auckland on 2 June that year.

They had one daughter, Helen, who was economic adviser to Prime Minister David Lange and rose to a prominent position with the World Bank.

In 2020 her son in law, Keith Ovenden, published "Bill and Shirley – a memoir" which does not mention Gaitanos' biography (the family had withdrawn cooperation during the writing of it).