The archbishop of Canterbury is the "Primate of All England" (the "first bishop" of England), effectively serving as the head of the established Church of England and, symbolically, of the worldwide Anglican Communion. From the 6th century to the 16th century, the archbishops of Canterbury were in full communion with the Bishops of Rome, the Popes. Eighteen archbishops have been canonised by the Roman Catholic Church. During the English Reformation the English church broke away from the authority of the Pope, at first temporarily, later permanently, recognising only the English monarch as a source of superior temporal authority. In the Middle Ages there was considerable variation in the nomination procedure of the archbishop and other bishops. At various times the nomination was made by the Canons of Canterbury Cathedral, the English monarch, or the Pope. Since the Reformation, the church is explicitly a state church and nomination is legally that of the British crown; today it is made in the name of the monarch by the prime minister of the United Kingdom, from a shortlist of two selected by the Crown Nominations Commission, an ad hoc committee. Today the archbishop has four main roles: He is the diocesan bishop of the Diocese of Canterbury, which covers the east of the County of Kent and the extreme north-east of Surrey. Founded by Augustine of Canterbury in 597, it is the oldest bishopric in the English church. The main duties of this role are delegated to the suffragan Bishop of Dover (who in this capacity is called the "Bishop in Canterbury"). He is the metropolitan bishop of the Province of Canterbury, encompassing 30 dioceses in the southern two-thirds of England. The remaining 14 dioceses in the north of England fall within the Province of York, under the authority of the archbishop of York. Four dioceses in Wales were under the Province of Canterbury until they were transferred to the dis-established Church in Wales in 1920. As "Primate of All England", he is the chief "religious" figure in the Church of England (senior to the archbishop of York, who is styled the "Primate of England"). The British sovereign is the supreme governor of the Church of England. As symbolic head of the Anglican Communion, the archbishop is recognised as primus inter pares ("first among equals") of all Anglican primates. Heraldry Much heraldry relating to archbishops of Canterbury is displayed in the church of