Opposed to World War I, he joined the British Socialist Party (BSP) and was elected to its central committee in 1918.
[1] During this period, McLaine worked with William Leonard and John Maclean in running classes for the Scottish Labour College.
[3] McLaine then attended the 2nd World Congress of the Comintern, along with Sylvia Pankhurst,[4] Marjory Newbold, Willie Gallacher and others, McLaine and Tom Quelch representing the BSP which shortly afterwards became part of the Communist Party of Great Britain (CPGB).
Whilst in Moscow McLaine was appointed to the Provisional International Bureau and the Executive Committee of Kultintern.
He contacted Frank Chapple, Nancy Hewitt and Billy Hughes who worked together as a team to deliver the course.