Patrick Johnstone was brought up in England as the eldest of six siblings, children of an Irish father and a Dutch mother. He was converted to Christ in 1959 during his first year as a student at Bristol University while studying chemistry in preparation to become a research scientist. At a Christian Union meeting, he heard Glyndwr Davies speak about the evangelistic work of the Dorothea Mission in urban townships in southern Africa, and he rose to the challenge and committed his life to serve as a missionary evangelist.
Patrick served in Kenya, South Africa, and Zimbabwe (then Rhodesia), and it was during this time that he also began the work of gathering data about the world both to inform prayer and for the first editions of Operation World. Over 2.5 million copies have been distributed around the world in seven editions and some 16 languages, and the book has played a key role in developing the global vision of African, Latin American, and Asian missions.
In 1995, Patrick married Robyn Erwin from the U.S., and the couple now lives in Cambridgeshire, England, where they currently serve as regional directors for Worldwide Evangelization for Christ (WEC) European bases.