Locke served on the Wellesley, Massachusetts, Board of Selectmen from 1959 to 1962 and was the board's chairman from 1961 to 1962. From 1961 to 1969 he was a member of the Massachusetts House of Representatives. He then served in the Massachusetts Senate from 1969 to 1993. He was the Assistant Minority Floor Leader of the Senate from 1971 to 1989 and Minority Floor Leader from 1989 to 1993.[2] He was defeated by Cheryl Jacques in 1992.[4]