How did the murder of St. Thomas Becket affect the relationship between Church and State in England 1170-1215?

The murder of St. Thomas Becket in 1170 was a significant event in defining the relationship between Church and State in Mediaeval England. It called into question the validity of the King's authority, and the extent to which the Papacy were able to claim political, as well as spiritual, supremacy in England. The murder served to significantly change the relationship between Church and State in England in several ways, and also played a part in bringing about Magna Carta in 1215, the consequences of which are still relevant to English politics today.