John Ambrose Cyril Mantle was ordained in Scotland and served as a priest in both the Scottish Episcopal Church and the Church of England. In 1980, he became Chaplain of Fitzwilliam College, Cambridge, moving to become staff tutor and Vice Principal of the Canterbury School of Ministry.He was the Archbishops’ Adviser for Bishops’ Ministry in the Church of England for a number of years before his election to the bishopric. In 1998, he completed his Ph.D. with the University of Leeds, writing a dissertation on British worker-priests in the early 1950s and '60s (later published by SCM).

He was consecrated Bishop of Brechin on Saturday, October 8, 2005, aged 59.

His father was a priest for many years in both Dundee and Aberdeen. John Mantle is married to Gill Mantle, they have two children Anna and Tim.

Mantle, John (1999). Britain's First Worker-Priests: Radical Ministry in a Post-War Setting. London: SCM. ISBN 0334027985.