In the seventh century, the Scots brought the Gospel to the English kingdom of Northumbria. The Northumbrian king had been in exile to the Scottish island of Iona, where he and his companions stayed at the famous Celtic monastery.
The Celtic Church in England
On returning to York and becoming king, he asked the Scots to send missionaries to his people, and the Scots came over bearing the Gospel. The Romans had long departed from Hadrian's Wall, thus there was nothing preventing the Celtic Church spreading from Scotland to England.
With the Gospel, the Scots Christianised northern England.