In 1909, he became a tram conductor, and he joined the Amalgamated Association of Tramway and Vehicle Workers, soon winning election to its national executive.
He joined the Labour Party in 1909, and in 1913 became a full-time officer of the trade union.
He also became involved in the Rochdale Trades and Labour Council, serving on its executive for five years.
[5] During the year, the union merged into the United Vehicle Workers, which appointed him as its Lancashire organiser.
In 1922, the union took part in a further merger, which formed the Transport and General Workers' Union, and McLean became an Area Passenger Transport Group Secretary, remaining in the post until he retired in 1942.