The son of Edward Atheling and grandson of Edmund Ironside, Edgar was the king which England never had. His family were in exile under the Viking kings, and were believed dead, until they were found in Hungary. Edward was called home by Edward the Confessor, to become his heir, but died mysteriously shortly after landing in England. Edgar then became a potential heir, but in the event the throne was seized by Harold Godwinson. On his death in 1066CE, in battle against the Norman William the Conqueror, Edgar was proclaimed king by the royal council in London. He was, however, far too young, being only about 14 years old, and William took the throne, Edgar submitting to him.
In 1068 Edgar was drawn into a revolt by the earls of Mercia and Northumberland, and, this failing, was obliged to flee to Scotland, with his sister Margaret. There they were sheltered by Malcolm III, who married Margaret and supported Edgar. Edgar's ill-luck or ill-judgement continuted: reconciled with William in 1072, on William's death he picked the wrong brother to support and under William Rufus he had again to flee to Scotland, where he became involved in the succession conflict between Edgar I and Donald III.
Around 1098 it appears that he went to Constantinople and became involved in the First Crusade. He returned to Europe and fought for the wrong side at the battle of Tinchebrai. Repatriated to the England of Henry I, who had married his neice Edith (otherwise Matilda) he was again pardoned and retired into obscurity, possibly dying in Scotland.