Osbeorn Bulax's father governed on what king's behalf?
Osbeorn Bulax Osbeorn (died c. 1054), given the nickname Bulax, was the son of Siward, Earl of Northumbria (died 1055). He is one of two known sons — probably the older — of Siward. While it is normally assumed he was the son of Siward's Bamburgh wife Ælfflæd, it has been suggested by William Kapelle that Osbeorn's mother was not Ælfflæd. The nickname "Bulax" probably represents the Old Norse term for "Poleaxe".
Æthelswith Æthelswith (c. 838–888) was the only known daughter of King Æthelwulf of Wessex. She became Queen Æthelswith when she married King Burgred of Mercia in 853. The couple had no issue. Her marriage probably signalled the subordination of Burgred to his father-in-law and the Saxon kingdom at a time when both Wessex and Mercia were suffering Danish (Viking) raids. Burgred also had ongoing problems with the Kingdom of Powys on his western border and in 853 Æthelwulf subjugated the Welsh state on Burgred's behalf.