He was wounded at the Anzio Bridgehead, an event that led him to question the compatibility of his army service with his sense of calling to Christian ministry.
From a Plymouth Brethren background, Wallis came into the experience of the "baptism with the Holy Spirit" in 1951, within a few weeks of his lifelong friend, the former Southampton City Missioner, Oscar Penhearow.
Following in his father's footsteps, Wallis then embarked on an itinerant preaching and teaching ministry, with a particular emphasis on revival, prayer, the work of the Holy Spirit, and the 'restoration' of the church.
'[3] Dr Martyn Lloyd-Jones reportedly took delight in a cogent article authored by Wallis in Theological Renewal arguing that baptism in the Holy Spirit is a distinct and separate experience.
[4] In an article in Restoration magazine entitles Women in the Plan of God he wrote "The church and the world has yet to feel the impact of modern Priscillas and Phoebes, moving under the heavenly anointing and yet within the divine order.