A church council that resolved the differences between the Celtic and Roman forms of Christian worship in England, particularly the method used for calculating the date of Easter. The Celtic Church had its own method of fixing the date of Easter; this was a matter of dispute after the arrival of St Augustine of Canterbury’s mission. The Celtic case was presented by St Colman, Bishop of Lindisfarne. The Roman case was put forward by St Wilfrid of Ripon, whose arguments were finally accepted by King Oswy of Northumbria. This decision was crucial, severing the connection with the Irish church and allowing for the organization of the English church under Roman discipline. Theodore, Archbishop of Canterbury, summoned an assembly of the whole English church at Hertford in 672.