Stanley John Kennett was born in Ipswich 5 May 1906 and attended Northgate School in Ipswich and later the London School of Mines. His parents were Unitarians. He graduated from Imperial College, London and later gained a doctorate. He became an Assistant Lecturer in Metallurgy at the University of Liverpool in 1928 and was promoted to Lecturer in 1931. He was Acting Head of Department from 1941 and then a Senior Lecturer from 1956 until his retirement in 1972. He became a Fellow of the Institution of Metallurgists in 1946 and was Founder President of the Liverpool Metallurgical Society from 1948 until 1950.

Kennett was very involved in the Unitarian Church. He attended the annual General Assembly of the Unitarian and Free Christian Churches from 1929 until 1991 and was President in 1964-1965. He was one of five honorary members of the General Assembly. He was also involved in the World University Service which worked to provide training in developing countries and became part of its executive. As well as this he was involved with the International Association for Religious Freedom.

Kennett was very interested in the arts. He was the first associate member of the Royal Liverpool Philharmonic Society in 1930 and from 1988 was its honorary vice-president. He was also on the Merseyside Arts Committee and supported Merseyside Youth Orchestra. He was acquainted with many musicians including Benjamin Britten.

Kennett was also involved in politics, first the Labour party and later the Social Democrat and Liberal Democrat parties. He married Millicent Curran in 1952. He died 11 May 1992.