In the early 12th century, William of Malmesbury wrote that she suffered from an illness during the last few years of her life, but there may have been some confusion with details of Æthelgifu's life as recorded in a forged foundation charter of the late 11th or 12th century (see below).
I begyndelsen af det 12. århundrede skrev William af Malmesbury, at hun led af en sygdom i løbet af de sidste par år af hendes liv, men der kan have eksisteret en vis forvirring onkring detaljerne i Æthelgifus liv som et resultat af et forfalsket dokument fra 11. eller 12. århundrede (se nedenfor).