In 635 Aidan, an Irish monk from Iona, chose the Isle of Lindisfarne to establish a monastery which was close to King Oswald's main fortress of Bamburgh. He had been at the monastery in Iona when Oswald asked to be sent a mission to Christianise the Kingdom of Northumbria from their native Anglo-Saxon paganism. Oswald had probably chosen Iona because after his father had been killed he had fled into south-west Scotland and had encountered Christianity, and had returned determined to make Northumbria Christian. Aidan achieved great success in spreading the Christian faith, and since Aidan could not speak English and Oswald had learned Irish during his exile, Oswald acted as Aidan's interpreter when the latter was preaching. Later, Northumberland's patron saint, Saint Cuthbert, was an abbot of the monastery, and then Bishop of Lindisfarne. An anonymous life of Cuthbert written at Lindisfarne is the oldest extant piece of English historical writing, and in his memory a gospel (known as the St Cuthbert Gospel) was placed in his coffin. The decorated leather bookbinding is the oldest intact European binding.