Editing Northumbria (section)

===Synod of Whitby===
{{main|Synod of Whitby}}
In 664, King [[Oswiu]] called the Synod of Whitby to determine whether to follow Roman or Irish customs. Since Northumbria was converted to Christianity by the Celtic clergy, the Celtic tradition for determining the date of [[Easter]] and Irish tonsure were supported by many, particularly by the Abbey of [[Lindisfarne]]. Roman Christianity was also represented in Northumbria, by [[Wilfrid]], Abbot of [[Ripon]].  By the year 620, both sides were associating the other's Easter observance with the Pelagian Heresy.<ref>{{harvnb|Corning|2006|p=114}}</ref> The King decided at Whitby that Roman practice would be adopted throughout Northumbria, thereby bringing Northumbria in line with Southern England and Western Europe.<ref name="auto2">{{harvnb|Bede|2008}} Book III chapter 25–26</ref> Members of the clergy who refused to conform, including the Celtic Bishop Colman of Lindisfarne, returned to Iona.<ref name="auto2"/> The episcopal seat of Northumbria transferred from Lindisfarne to York, which later became an [[Archbishop of York|archbishopric]] in 735.<ref name="auto3">{{harvnb|Rollason|2003|pp=239}}</ref>