Æthelsige was an Abbot of Abingdon and succeeded Wulfgar

Wulfgar of Abingdon

Wulfgar, Abbot of Abingdon was appointed Abbot of Abingdon in 990 AD and died in 1016. An advisor of King Ethelred, he is praised in the Chronicle of Abingdon as a good leader who won restitution of Abingdon lands alienated by the king...

 in 1016 (Anglo-Saxon Chronicle, version C).

He lived in the town today called Elswick

Elswick, Lancashire

Elswick is a rural village and civil parish in the English county of Lancashire, situated on the coastal plain called the Fylde. As of the 2001 United Kingdom census, the parish had a population of 1,057. At the time of the Norman conquest of England in 1066, Elswick was a small agricultural...

, known then as "'Edelesuuic," literally "the farm of a man named Æthelsige." Before he died in 1018 he was principal in the treaty between Danes and English to observe the laws of Edgar. He was succeeded by his son Æthelwine (Anglo-Saxon Chronicle

Anglo-Saxon Chronicle

The Anglo-Saxon Chronicle is a collection of annals in Old English chronicling the history of the Anglo-Saxons. The original manuscript of the Chronicle was created late in the 9th century, probably in Wessex, during the reign of Alfred the Great...

, version E).