Smith was first active in local politics as a Liberal in 1945 before switching to Labour in 1950; he served as a Labour councillor in Rochdale from 1950 and became mayor in 1966. He subsequently switched parties again and entered Parliament as a Liberal in 1972 and won his Rochdale seat on five further occasions. Smith was appointed the Liberal Chief Whip in June 1975 but later resigned on health grounds. In his later years as an MP, Smith opposed an alliance with the Social Democratic Party and did not stand for re-election in 1992, but remained loyal to the Liberal Democrats upon the parties' merger. Throughout much of his career, he maintained a high profile in the media, and became a popular public figure.