Douglas was converted through the witness of a friend at school, and subsequently trained for ministry at London Bible College. Here he was one of the many young men who came under the influence of Dr. Ernest Kevan, the first principal of the college, who helped Douglas’s understanding of the doctrines of grace, and did much to influence his subsequent ministry. In 1954 he married Muriel (Parker), and began his ministry in East London. He was then called to a pioneering work: Arnold Road Evangelical Church in Nottingham. Douglas had a heart for people and for gospel work, including open-air preaching, and ministry to children from the local estate. He later served at churches in the Bristol area, and Wolverhampton. His clear and faithful preaching ministry was much appreciated.