There is some controversy over the exact date of Deusdedit's death, owing to discrepancies in the medieval written work that records his life.

[5] He was the sixth archbishop after the arrival of the Gregorian missionaries,[6] and the first to be a native of the island of Great Britain rather than an Italian, having been born a West Saxon.

[8] Deusdedit probably owed his appointment to the see of Canterbury to a collaboration between Eorcenberht of Kent and Cenwalh of Wessex.

[1] It is unclear when Deusdedit adopted his new name, although the historian Richard Sharpe considers it likely to have been when he was consecrated as an archbishop, rather than when he entered religious life.

[11] He was long overshadowed by Agilbert, bishop to the West Saxons,[12] and his authority as archbishop probably did not extend past his own diocese and that of Rochester, which had traditionally been dependent on Canterbury.

[1] The Synod of Whitby, which debated whether the Northumbrian church should follow the Roman or the Celtic method of dating Easter, was held in 664.

[5] Bede, in the Historia ecclesiastica gentis Anglorum, states that "On the fourteenth of July in the above mentioned year, when an eclipse was quickly followed by plague and during which Bishop Colman was refuted by the unanimous decision of the Catholics and returned to his own country, Deusdedit the sixth Archbishop of Canterbury died.

[14] Other historians, including Richard Abels, P. Grosjean, and Alan Thacker, state that Deusdedit died on 14 July 664.

Although Bede does not describe either Eorcenberht or Deusdedit's symptoms he does discuss another victim of the 664 disease, who suffered from a tumour on his thigh, resembling the characteristic groin swellings of bubonic plague.

A hagiography, or saint's biography, on Deusdedit was written by Goscelin after the translation of his relics, but the work was based mainly on Bede's account;[1] the manuscript of the De Sancto Deusdedit Archiepiscopo survives as part of British Library manuscript (ms) Cotton Vespasian B.xx.