He was a member of the South Australian House of Assembly from 1918 to 1950, representing the electorates of West Torrens (1918–1938) and Hindmarsh (1938–1950).
[1] McInnes was born in Scotland and moved to South Australia as a child.
He was the inaugural secretary of the South Australian Government General Workers' Association from 1905 to 1911.
McInnes was then general secretary of the Liquor Trades Employees Union from 1914 to 1924.
Later, he served as state president of the Labor Party from 1927 to 1929 and mayor of the Town of Hindmarsh from 1933 to 1939.