The episcopate of Cuthbert as bishop of Lindisfarne was a product of a time of great change in the Northumbrian Church in the late seventh century. Bede's Ecclesiastical history and Stephen's Life of Wilfrid make it clear that the expulsion of Wilfrid, bishop of York and sole bishop of the Northumbrians, in 678 (HE v. 19; VW 24) opened up the Northumbrian diocese to large-scale ecclesiastical reorganisation. Wilfrid's vast see was divided and new bishops appointed. In 664, as a young man, Wilfrid had played a significant part at the Council of Whitby in bringing about the expulsion of Colmán, Aidán's successor as bishop of Lindisfarne, the termination of the Columban mission and the replacement of the see of Lindisfarne by that of York; but the bishops who replaced Wilfrid were prepared to deal sensitively with the legacy of Aidán's mission in a post-Council of Whitby era. Bosa, trained at Whitby under Abbess Hild who had been instructed in the religious life by Aidán, became bishop of Deira at York; Eata, abbot of Lindisfarne, one of Aidán's Northumbrian disciples and formerly abbot of the monastery of Melrose which had been founded in the time of the Columban mission, became bishop of Bernicia with his episcopal seat variously at Hexham and Lindisfarne; and Eadhæsd, a former companion of Aidán's disciple Chad (HE iii. 28), was made bishop of Lindsey (HE iv. 12). When Lindsey was lost to the Mercians in 679 Eadhæd was made bishop of the short-lived see of Ripon [HE iv. 12), and in 681 Trumwine, whose antecedents are unknown but who later retired to Whitby, became bishop of Abercorn on the Forth [HE iv. 12, 26).