Thorulf's period of appointment coincided with the reign of Earl Thorfinn Sigurdsson, alleged builder of the Birsay church and founder of the bishopric of Orkney.
According to the late 11th-century Saxon writer Adam of Bremen, he was appointed as bishop of Blascona in Orkney by Adalbert, Archbishop of Hamburg.
Adam leaves no personal details about Thorulf, but supplies some information about the Orkney see, stating that the: ...Orkney Islands, although they had previously been ruled by English and Scottish bishops, our primate [Adalbert] on the pope's order consecrated Thorulf bishop for the city of Birsay [in civitatem Blasconam], and he was to have cure of all.
[9] Although this specific claim may not be true [one previous bishop is known], it is nevertheless taken as evidence that Thorfinn's reign was a significant turning point for the earldom,[10] suggesting according to historian Ronald Cant "a deliberate plan on the part of the earl to perfect the organization of the church in Orkney".
[11] Thorfinn and Thorulf's Christ Church has been identified with the Romanesque ruins on the tidal island known as Brough of Birsay, but there is also evidence that it was located over in the Mainland next to the Earl's palace.