Ian Trevor Sinnamon, born 6 January 1935, graduated from the University of Queensland with a Bachelor of Architecture in 1958. During his final years of study, he worked part-time with firms such as Prangley and Crofts. After graduating, he was awarded an Italian Government scholarship for postgraduate study at the University of Rome. Following brief working stints in Rome and London, he returned to Brisbane in 1960 and formed a short-lived partnership with John Hitch.

Sinnamon was a strong advocate for heritage conservation in the built environment. He served on the National Trust of Queensland’s Listings Committee from 1972 to 1984 and established its Conservation and Restoration Committee in 1979. From 1988, he was a member of the Heritage Advisory Committee under the Ahern and Goss Governments and contributed to the Green Paper Committee for Heritage Legislation, which led to the establishment of the Queensland Heritage Council in 1992. He also served on the Council’s Heritage Register Assessment Committee.

Sinnamon held positions as a lecturer and Head of the University of Queensland's Department of Architecture, and later took on the role as the Department's in-house historian, compiling its history and reflecting on the challenges of architectural education for the school's fiftieth anniversary in 1987.