Following studies at the University of Adelaide and the SA School of Mines, Hugh Angwin joined the Public Works Department in 1911 as a draftsman. After brief service in the AIF during the First World War, he was assistant resident engineer, River Murray Works, Blanchetown, before moving to Adelaide as assistant construction engineer. He later served as chief engineer and commissioner to the SA Harbours Board.
In his role as engineer-in-chief of the Engineering and Water Supply Department, the contribution of Hugh Angwin to the development of South Australia cannot be underestimated. Projects undertaken by him include the Morgan to Whyalla pipeline, the Barossa to Salisbury pipeline and the Mannum to Adelaide pipeline, the Glenelg sewage treatment plant, the completion of the Mt Bold reservoir and the design of the South Para reservoir. His department was responsible for the development of the Leigh Creek Coal Fields and he was chairman of the newly formed Electricity Trust of South Australia.