 The anonymous author of the earliest Life places Dunstan 's birth during the reign of Athelstan , while Osbern fixed it at " the first year of the reign of King Æthelstan " , 924 or 925 . This date , however , cannot be reconciled with other known dates of Dunstan 's life and creates many obvious anachronisms . Historians therefore assume that Dunstan was born around 910 or earlier . 
