Dumnonia
The ruler of Dumnonia was King Oswallt ap Cawrdolli (probably, his reign's exact dates are unknown).
Kent
The ruler of Kent was King Æthelberht II, who had ruled since 725 and would continue to do so until 762.
Mercia
The ruler of Mercia was King Offa, who had ruled since 757 and would continue to do so until 796.
Northumbria
The ruler of Northumbria was King Æthelwald Moll, who had ruled since 759 and would continue to do so until 765.
Fortriu
The ruler of Fortriu was King Óengus I .
Wessex
The ruler of Wessex was King Cynewulf, who had ruled since 757 and would continue to do so until 786.