He was elected Member of Parliament for the Farnworth constituency in Lancashire at a by-election in 1938 and held the seat until his death in 1952, aged 62.

He was joint Parliamentary Secretary under Ernest Bevin in the Ministry of Labour and National Service from February 1941 to May 1945 in Winston Churchill's wartime Coalition Government.

In 1944 Tomlinson was a British delegate at the International Labour Conference held at Philadelphia in the United States.

[1] A biography of Tomlinson written by Fred Blackburn, a fellow Labour politician and Member of Parliament for Stalybridge and Hyde, was published by Heinemann in 1954.

The biography, which features a foreword by Clement Attlee, is largely based on talks Blackburn had with Tomlinson before his death.