During his first six-year term on the field, Patrick served in Kenya, South Africa and Zimbabwe (then Rhodesia). In the last of these, he led the first Dorothea Mission team in evangelistic outreach in towns and cities across the country. He learnt a number of African languages, including siNdebele, chiShona and Afrikaans, and also became involved in translating part of the New Testament into chiNambya, a language spoken in northwest Zimbabwe.
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. The first printed booklet with that title, which came out in 1965, was just 30 pages long. The second edition appeared in 1973 and covered nearly every country of the world. It was reprinted several years later by Ralph Winter of the USCWM, and also prompted George Verwer to set in motion an OM-backed rewrite of the book for global distribution. This was completed in 1978 and led to many openings for wider ministry. The impact of Operation World is incalculable. 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.
The 1978 edition also led to some big changes in Patrick's ministry. The first was to join the OM ship, the MV Logos, for a year in Asia and the Pacific in 1979. The second followed an invitation to become part of the leadership team of WEC International, a large pioneer church-planting mission. Patrick's main responsibilities in 1980 were strategy and research and he worked in that role for the next 22 years, playing a part in the considerable growth of the mission as it addressed new unreached peoples and countries. For six years, he was also WEC's deputy international director.
Patrick was long involved with the Lausanne Movement. During the 1980s, he was a member of the Strategy Working Group that helped to formulate many of the definitions for its ethno-linguistic peoplegroup databases. In the '90s, he was co-leader with John Robb of World Vision of the "unreached peoples track" of the AD2000 and Beyond Movement. He has worked closely with David Barrett and Todd Johnson of the WCE and other researchers in sharing information and developing databases, and also played a part in the formation of Global Mapping International (GMI) and the Joshua Project and its listing of people groups.
Jill became ill with cancer in 1990 but she continued to write her children's version of Operation World and had almost completed it by the time of her death in 1992. The book was published as You Can Change the World, and later (by Daphne Spraggett) as Window on the World.
In 1995, Patrick married Robyn Erwin from the US, who had been a co-worker with Jill before her death. Patrick and Robyn now live in Cambridgeshire, England, where they currently serve as regional directors for WEC's European bases.