Prosser believed strongly that the Anglican Church in Wales was the true Catholic Church in Wales and that both the Roman Catholic and Nonconformist Churches were no more than "Intruders", as evidenced by his statement in 1946 (which he repeated in May 1949):
"The Roman clergy and Noncomformist ministers are intruders… There may be historical excuse for their being here, but we cannot recognise their right to be here…"[4]