Monsignor John O'Connor (1870-1952), an Irish parish priest in Yorkshire blessed with a solid continental education, was the inspiration for G.K. Chesterton's famous clerical sleuth, Father Brown. Though a friend of Chesterton and Eric Gill and a published writer himself, O'Connor's motives for printing his prewar tract on liturgical renewal both privately and anonymously will not be hard to fathom. His liturgical views offer an insight into the thinking of non-specialist advocates of the Liturgical Movement in the late 1930s. Always strident, his liturgical opinions are sometimes prophetic and often confounding. Immune to neat categorisation, this liturgical manifesto from the real "Father Brown" may surprise many admirers of the beloved character he inspired.