H. P. Grice and G. J. Warnock

Warnock was born in Leeds, in northern England, and was educated at Winchester College. He then served with the Irish Guards until 1945, before entering New College, Oxford, with a classics scholarship. He was elected to a Fellowship at Magdalen College, Oxford, in 1949. After spending three years at Brasenose College, he returned to Magdalen as a Fellow and tutor in philosophy. In 1970, he was elected to Principal of Hertford College, Oxford (1971–1988), where there is now a society and student house named after him. He was also the Vice-Chancellor of the University of Oxford from 1981 to 1985.

Warnock and his co-editor J. O. Urmson performed an invaluable service to the development of "analytic" or "linguistic" philosophy by preparing for publication the papers of their friend and fellow Oxford linguistic philosopher J. L. Austin.

Warnock married Mary Warnock, a philosophy fellow of St Hugh's College, Oxford, and later Baroness Warnock, in 1949. They had two sons and three daughters. He retired to live near Marlborough, Wiltshire, in 1988 and died in 1995 at Axford in Wiltshire.