He was made a School and Technical College Governor in 1955 and served on Bolton Town Council from 1958 to 1960, being Vice-Chairman of the Housing Committee.
He was the Labour candidate for the Conservative-held seat of Bolton East at the 1960 by-election, but lost by 641 votes.
In 1963 he was again elected to Bolton Town Council, serving until 1966 and becoming Vice-Chairman of the Planning Committee.
He became a Lecturer in Liberal Studies at Leigh Technical College that year, remaining in the post until 1976.
From 1977 to 1987, when he retired, Howarth was Senior Lecturer in General Studies at Wigan College of Technology.
He did not stand for Parliament again, although his old seat was again gained by Labour at the subsequent general election in February 1974.