His studies were interrupted by the Second World War, when he joined the Free Thai resistance movement opposed to the pro-Japanese military regime of Plaek Phibunsongkhram.

[2] As governor, he played a central role in shaping Thailand's economic development policies during the governments of Field Marshals Sarit Thanarat and Thanom Kittikachorn.

Equally important, this international recognition gave him an influence with Field Marshals Sarit Thanarat, Thanom Kittikachorn, and their cohorts which far exceeded his bureaucratic position.

After stepping down as central bank governor, Puey was appointed to the un-elected National Legislative Assembly established under the interim constitution of December 1972 in the aftermath of Thanom's 1971 auto-coup.

After Thanom's junta was ousted in a popular uprising in 1973, Puey was chosen by caretaker prime minister Sanya Dharmasakti, who had also served as Rector of Thammasat University, to chair the government's Economic Advisory Council.

In 1966 Puey became the dean of the Faculty of Economics at his alma mater, Thammasat University, where his work with the Rockefeller Foundation and with foreign scholars dramatically upgraded the training of Thailand's future technocrats.

Puey played an instrumental role in the establishment of the Bangkok-based Asian Institute of Technology (AIT),[6] previously the Graduate School of Engineering of the Southeast Asia Treaty Organization (SEATO)[7] in 1967.

Kukrit Pramoj, was broadly promoted as one of the two major candidates for the post of prime minister in the elected government that would follow the palace-picked interim administration of Sanya Thammasak.

Some have argued, however, that Puey's withdrawal was based upon his mature understanding of the nature of society and that he had accurately foreseen that the upcoming democratic period would be inherently unstable, dangerous, and short-lived.

On the evening of the bloody 6 October 1976 Massacre, Puey resigned from his position as rector of Thammasat in protest against the bloodbath that had occurred that day on the university campus.

In 1977, Puey gave testimonials before the House Committee on Foreign Affairs investigating human rights in Thailand following the incident of 6 October 1976 Massacre.