He was a supporter of the Labour Party, and at the 1935 United Kingdom general election, was selected as its candidate in Glasgow Bridgeton.
However, the seat was held by James Maxton, the popular leader of the Independent Labour Party, and McLaren took last place, with only 2.2% of the vote.
[1][2] McLaren next stood for Parliament in East Fife at the 1945 United Kingdom general election, as a Labour Co-operative candidate.
By 1959, he was the assistant and financial secretary of the UPA, and had relocated to work at its head office in London.
Under his leadership, the union attempted to broaden its membership, by renaming itself as the Association of Patternmakers and Allied Craftsmen.