One holder of this office used the word "thorough" to describe his campaigns for conformity, which drew the disdain of Henrietta Maria. William Laud held this office, which had its power to convene courts limited by the Constitutions of Clarendon. The first of them was a foreigner on mission from Gregory the Great, named Augustine, and four knights responded to a rhetorical question by murdering another during Henry II's reign. While in this role, Thomas Cranmer wrote the Book of Common Prayer. For 10 points, name this 
One holder of this office used the word "thorough" to describe his campaigns for conformity, which drew the disdain of Henrietta Maria. William Laud held this office, which had its power to convene courts limited by the Constitutions of Clarendon. The first of them was a foreigner on mission from Gregory the Great, named Augustine, and four knights responded to a rhetorical question by murdering another during Henry II's reign. While in this role, Thomas Cranmer wrote the Book of Common Prayer. For 10 points, name this office once held by Thomas Becket, the leader of the Church of England.
One holder of this office used the word "thorough" to describe his campaigns for conformity, which drew the disdain of Henrietta Maria.
Archbishop of Canterbury [prompt "bishop" or "archbishop;" prompt "Primate of All England"]