Goodwin joined the Labour Party in 1932, and began his political career when he was elected to Bermondsey Borough Council in 1937.
Goodwin became a member of the Greater London Council for Southwark after its first election in 1964 and chaired the Finance Committee in the Labour administration.
After the Conservatives won a landslide election victory in 1967 he was chosen as the new Labour Leader almost by default, other more dynamic personalities having been defeated.
Labour had not opposed the Conservative GLC's policy of building urban motorways in 1970 but by June 1972 Goodwin had been convinced by the strength of public opinion, and said "Labour pledges itself to abandon the disastrous plans to build two motorways which threaten the environment of Central London".
It had a distinctly left-wing approach favouring subsidies to reduce (possibly eliminate) public transport fares and to build more council homes, but Goodwin supported these policies and gave his backing to the manifesto which was published under the title "A Socialist Strategy for London".
By this manner Goodwin managed to continue the distinctly green agenda set in the 1973 manifesto despite many economic problems nationally that affected the GLC's finances.
Goodwin was forced to cut investment programmes and increase transport fares and as a result became unpopular with the left.