John Oldham was educated as a boarder at Guildford Grammar School and studied to become an architect at The University of Western Australia and Melbourne University. In Sydney, during the Depression, he established Oldham Publishing Company which produced lino cut posters and calendars.
Married to Ray Oldham (q.v.), they moved to Sydney and in 1939, John was given the task of designing the Australian Pavilion for the 1939 New York World Fair. In Sydney in 1940 Ray had the firest of their two daughters and John Oldham continued to work as an architect. In 1954, he returned to Perth where he designed a number of exhibitions for the Ministry of Post-War Reconstruction. Oldham turned to landscape architecture soon after.
Both Ray and John Oldham were very active in progressive and left-leaning organisations for most of their lives.