Although it is clear that Siward was earl by 1033, he may have attained the position somewhat earlier. His predecessor Erik of Hlathir last appeared in the historical sources in 1023, leaving a ten-year gap during which Siward could have taken the position. Although William of Malmesbury asserted that Erik was driven back to Scandinavia, Scandinavian tradition firmly maintained he died in England. Historian William Kapelle believed that Erik ceased to be earl in or soon after 1023, and that Carl son of Thurbrand was appointed hold or high-reeve (heahgerefa) for the king in Yorkshire. Carl retained this position, it was argued, even after Siward was installed as earl a few years later, but from then on he acted as a deputy to the earl rather than to the king. Richard Fletcher remained agnostic on the point, although he did argue that Erik must have been dead by 1028. Timothy Bolton, although rejecting Kapelle's argument concerning Carl son of Thurbrand, believed Erik died c. 1023 and that the earldom may have remained vacant for a period. Bolton argued that Cnut left the earldom of Northumbria empty and appears to have paid it little attention until the last years of his reign, and another northerner Ealdred son of Uhtred rose to power in the political vacuum. When Cnut died in 1035, there were a number of rival claimants for his throne. These included his son Harthacnut, and the nobleman Harold Harefoot, as well as Alfred Ætheling and Edward (later, King Edward the Confessor), the exiled sons of Æthelred the Unready. Isolated in Scandinavia, Harthacnut was unable to prevent Harold Harefoot seizing the crown for himself. Ruling England from 1035, Harold died in 1040 just as Harthacnut was preparing an invasion. Arriving soon after Harold's death, Harthacnut reigned in England only two years before his own death in 1042, a death that led to the peaceful succession of Edward. Frank Barlow speculated on Siward's political stance, guessing that during these upheavals Siward assumed "a position of benevolent or prudent neutrality". Siward is found in 1038, as Sywardus Comes ("Earl Siward"), witnessing a charter of King Harthacnut to the Abbey of Bury St Edmunds. He witnessed a confirmation granted by Harthacnut to Fécamp Abbey, between 1040 and 1042, of an earlier grant made by Cnut. In 1042, he witnessed grants by Harthacnut to Abingdon Abbey and to Ælfwine, Bishop of Winchester. Siward was,