Angmendus may have held the role of the first

Lord Chancellor The lord chancellor, formally the lord high chancellor of Great Britain, is the highest-ranking traditional minister among the Great Officers of State in Scotland and England in the United Kingdom, nominally outranking the prime minister. Th ...

(of the

Kingdom of Kent la, Regnum Cantuariorum , conventional_long_name = Kingdom of the Kentish , common_name = Kent , era = Heptarchy , status = vassal , status_text = , government_type = Monarchy ...

), being appointed in 605, during the reign of Æthelberht of Kent (Ethelbert).
The lives of the lord chancellors and keepers of the great seal of England, Baron John Campbell, 1851 Other sources suggest that the first ruler to appoint a Chancellor was Edward the Confessor, who is said to have adopted the practice of sealing documents instead of personally signing them.

References

Further reading