In January 1990 he became the Chief of the General Staff, and he was responsible for the Army. Later in 1991 he became appointed as the Assistant Chief of the General Staff for Material, which also included taking care of the Army equipment and building projects. On the first of November 1993, he was sworn in as the 27th governor of Western Australia, and he also became a Companion of the Order of Australia, until 2000. General Jeffery's interests were about young people, education, environment, and national security. Also, the Queen made him the Prior for Australia, and a Knight of Justice of the Order.