927. Sihtric of Northumbria dies
Guthfrith succeeds to Northumbria, but is driven out by Æthelstan
Sihtric's death is recorded in the Anglo-Saxon Chronicle. One manuscript goes on to say that Æthelstan succeded him without mentioning any other claimants, while another notes that Æthelstan drove out a King Guthfrith. Sihtric left a son, Olaf Cuaran, who would return to seize York after Æthelstan's death in 939. Guthfrith was Sihtric's brother and Olaf's uncle, and after being expelled from York by Æthelstan went back to being king of Dublin.
R. Mynors and others, William of Malmesbury: Gesta Regum Anglorum (Oxford: 1998)
A. Smyth, Scandinavian York and Dublin (Dublin: 1975-8)