He completed primary school and received some secondary education in Antigua.
He joined the Antigua Trade and Labour Union (ATLU) during the 1950s and became the union’s general secretary and primary negotiator. He acquired the reputation as an effective representative of the workers.
In the elections of 1976 the PLM, despite capturing a majority of the popular vote, was defeated by Bird's ALP. Walter became Leader of the Opposition. In 1980 his party won only 3 seats in the Legislative council. Walter continued as Leader of the Opposition after independence was achieved in 1981.
During the 1960s Walter became concerned about the conflict of interest in the highest reaches of government: many government officials also were executive of the ATLU. He led a group of the union's middle-level leaders in asking that the premier, Vere Cornwall Bird, and other government ministers resign from either their government or union positions. When Bird refused, Walter and his followers left the ATLU and formed a rival Antigua Workers Union (AWU), which immediately attracted a large number of workers.
Walter also formed the country’s first real political party, the Progressive Labour Movement (PLM), in April 1968. Formerly, politics was organized through the political committee of the ATLU, which used the name Antigua Labour Party (ALP), although not formally organized as a political party. With formation of the PLM. Walter resigned his position in the AWU.
Both parties contested the general elections in 1971. and Walter led his PLM to a stunning victory, winning 13 of the 17 seats. Walter became premier and immediately set about the task of agricultural development while closing down the last of the sugar factories on the island, which had been a financial disaster. His government expanded livestock production for both internal consumption and export, revived the production of sea island cotton, and developed fruit and vegetable output. It also established a social security system and comprehensive labor legislation.