William Jenkins was born on 25 July 1904 in the Whitehouse area of north Belfast. He was educated at Whitehouse School and the Belfast College of Technology.

In 1931, Jenkins joined the mill-owning company of J H Brady in Mumbai (formerly Bombay), India. He became the senior director of the company until his retirement from the role in 1956. He held various civic positions in India including Justice of the Peace and Bombay Honorary Presidency Magistrate.

Jenkins returned to Belfast in 1955 and entered the Belfast Corporation in 1957. He was made High Sheriff in 1961 and served three consecutive terms as Lord Mayor from 1963 to 1965.

In 1963, following Jenkins retirement from the Corporation, he was appointed Ulster Agent in London by the Northern Ireland Government. He was knighted in 1966.

Jenkins was a member of the senate of Queen’s University, a member of the Institute of Directors, and was chairman of the Northern Ireland Bureau from 1967 to 1975.