Hong Kong Federation of Trade Unions
A member of the traditional left-wing Hong Kong Federation of Trade Unions (FTU), Tam was a member of the Hong Kong Basic Law Drafting Committee (BLDC) and among the first elected members of the Legislative Council through the Labour functional constituency in 1985. He was the founding vice-chairman of the Democratic Alliance for the Betterment of Hong Kong formed in 1992 and its party chairman from 2007 to 2015.