Lathan worked on the railways where he became an active trade unionist and joined the Independent Labour Party. He became president of the Railway Clerks Association from 1906 until 1912, when he became its chief assistant secretary, a post he held until 1937.
Lathan was a parliamentary candidate at successive general elections. In 1922 he was defeated in Enfield, then in 1923 and 1924 he stood in Sheffield Park, finally winning the seat in 1929. He lost the seat in 1931, but retook it in 1935. He served as the chairman of the Labour Party National Executive Committee in 1931/2 and party treasurer from 1936 until his death.
References
Michael Stenton and Stephen Lees, Who's Who of British MPs: Volume III, 1919-1945