The Synod of Whitby resolved the differences between Irish and Roman practices. The decision, as presented by Bede, was as much that of King Oswiu as the church men present at the council.

The key difference lay in Irish and Roman traditions having different methods of calculating the date of Easter which could lead to Easter being celebrated on different Sundays. This was a particularly difficult matter for the royal household as Oswiu followed the Ionan practice of his youth whereas his queen, Eanflæd, Edwin’s daughter, kept to the Roman custom, leading to a situation where half the royal household was still keeping the Lenten fast while the other half was enjoying the Easter feast.

Such a visible sign of disunity was not tenable in a royal family and, indeed, it appears to have been one of the reasons for the strife between Oswiu and his son, Ahlfrith.