In 1955 he began teaching at Kwato mission, Milne Bay, an outpost of the Moral Rearmament Movement under whose auspices he visited New Zealand, the United States and Europe.

In 1957 he joined the Territory of Papua and New Guinea's administration as a teacher. He was headmaster of Kerepunu school in the Marshall Lagoon area when in 1962 he was recalled to Port Moresby to become assistant to Assistant Administrator John Gunther.

In the same year, he was elected president of the Port Moresby Workers' Association and Gunther, recognising his ability, gave him a number of specialised tasks including appointment as assistant executive officer for the Commission on Higher Education.

Oala-Rarua resigned from the Administration in 1965 to work full time for the new Federation of Workers' Associations which he had helped to establish. He also founded the short-lived New Guinea United National Party.

In 1967 he was a founding member and co-chairman of the Pangu Pati, but soon left because of policy differences. At the second House of Assembly elections in 1968 he was elected as member for the Central Regional Electorate and appointed assistant minister for the Treasury.

Oala-Rarua's contributions to debate were forthright, cogent and uncompromising. As a “straight-out nationalist”, he consistently argued for PNG’s advance towards independence and for “the betterment of its people regardless of colour, race, or creed”.

While urging PNG’s development as one nation, he recognised the imbalance in the allocation of funds which should be redressed in Papua's favour. He was a member of the important Select Committee on Constitutional Development which reported in 1971.

In the same year he was elected president of the Port Moresby Town Council and became its first mayor in 1972 after his defeat at the national parliamentary election.

In 1974, Oala-Rarua was chosen to set up PNG’s first diplomatic office in Australia and, at independence in 1975, he became the first high commissioner to Australia. At the end of his term in 1977 he returned to PNG and stood unsuccessfully as a candidate for the Moresby South Open.

Retiring from politics, he pursued business interests but died suddenly of cerebrovascular disease on 17 May 1980 in Port Moresby and was buried at Pari village.

Able, intelligent, personable and urbane, Oala-Rarua mixed easily with Australians, indigenous Papua New Guinea leaders and his own Motu people.

He was part of an elite group who carried the burden of the expectations of Papua New Guineans and Australian government officials as the country approached independence.

One of the few Papuans of his generation with education beyond primary level, he was thrust into responsibilities which did not always suit his talents or temperament.

Michael Somare paid tribute to him as “one of the pioneers of our nation, a wonderful man and a dedicated nationalist”.

Murray Groves, 'Oala-Rarua, Oala (1934–1980)', Australian Dictionary of Biography, National Centre of Biography, Australian National University, https://adb.anu.edu.au/biography/oala-rarua-oala-11270/text20105, published first in hardcopy 2000, accessed online 29 May 2021