Maclean was the first Secretary of the Socialist Labour Party, but was expelled in 1908. Then a member of the Independent Labour Party (ILP), Maclean worked closely with other socialists in the Glasgow area, as part of the Red Clydeside movement. Like many other Red Clydesiders, he was a conscientious objector in the First World War. He greatly influenced Manny Shinwell. An organiser for the Scottish Co-operative Wholesale Society, in the 1918 General Election Maclean was elected to the House of Commons to represent the Govan seat in Glasgow. When many of his fellow ILP Clydesiders left the Labour Party, Maclean remained a Labour MP, associating for a time with the Scottish Socialist Party.
He retired from Parliament in 1950, not having secured renomination. He was offered a seat in the House of Lords, but declined due to his socialist principles. He was appointed a CBE.
- "The London Gazette". The London Gazette. 28 January 1919. p. 1366. Retrieved 21 May 2018.
- The National Union of Conservative and Unionist Associations, Gleanings and Memoranda (1932), p. 500
- Hansard 1803–2005: contributions in Parliament by Neil Maclean