Rev J.A.P. Oswald served as a teacher, headmaster, and principal in seven aided and private mission schools from April 1919 to December 1964. In the postwar years, he was responsible for school extensions and building programmes in Sentul, Banting and Seremban.
The acquisition of educational sites and raising of funds in Banting and Seremban were among the crowning achievements of a distinguished career. At the Malaya Annual Conference in December 1965, Rev Oswald was given a certificate in recognition of his years of service as a teacher in Methodist schools.
In 1919, Rev W.E. Morley appointed Rev Oswald principal of the Anglo-Chinese School (ACS) in Malacca. When Oswald arrived, the school had 54 pupils with Standard Four as the highest class. He set about revamping the school administration with energy and enthusiasm. The student enrolment soon increased to 160 and two shophouses were rented at Kubu Road to cope with the higher admissions. New teachers were also recruited from Telok Anson, Ipoh and Kuala Lumpur.
In 1924, he was transferred to the ACS in Parit Buntar, Perak.
From 1950-1952, Rev Oswald became the principal of the Methodist Boys Primary School, Sentul. Under his leadership, eight new classrooms and a science laboratory were built. The house and prefect system was also introduced and the school published its first magazine called The Sentinel. It also applied for permission to start a secondary section and this was duly granted.
In 1952, the Methodist Church sent Oswald from Kuala Lumpur to Banting to start the Methodist English School (MES). On January 12, 1953 the school opened with five classes, 202 pupils and eight teachers. It was the first government-aided English school in Kuala Langat. He brought English education to Banting as up till then, only well-to-do parents could afford to send their children to Klang for primary and secondary English education. Oswald became the founding headmaster and served there until 1957. He also encouraged overaged pupils to attend the Methodist Afternoon School. Rev Oswald also became the first pastor of the Tamil Methodist Church, Banting.
In fact, wherever he had a school appointment, he was also pastor of the local Tamil Methodist Church. He travelled great distances to cover circuits and gave his time, money and energy and showed concern for the people in need of his counsel, help and spiritual leadership. Aside from Banting, the Tamil Methodist churches in Parit Buntar, Sentul and Seremban owe a great debt to him.
His four daughters served actively in the churches and one of them, Beatrice, graduated from the Harris Memorial School in Manila and served at the Ulu Klang Centre, Selangor, before getting married to Rev I.R. Arulpragasam, an Anglican minister in Ceylon (now Sri Lanka).
Rev Oswald’s home was the training ground for several young people not only for a career but for service to the church. Rev James K. Solamadan and Rev Samuel Chong of the Trinity College in Singapore belonged to the Oswald Home and acknowledged their spiritual indebtedness to him. Rev Oswald was a pioneer in the field of church stewardship and ministerial care. As the chairman of the Committee on World Services in the postwar years, he initiated the Pastor's Salary Pool, a fund which grew steadily each year to provide a capital sum from which the Malaya Annual Conference could derive an annual income. He also initiated the Pastor's Minimum Salary Scheme.
He did all these while serving as a school teacher and he had no personal benefit from these institutions. His own local church’s contributions to benevolence and support of all conference causes was high because he himself was a sacrificial giver. He made a significant contribution to the material and spiritual life of the Methodist Church in Malaya.