This timeline is originally by Theophilus.
The principal POD of this ATL is the killing of the pagan king Penda of Mercia by Oswald of Northumbria, instead of the latter being killed and dismembered by the former, at the Battle of Maserfield on August 5, 642. Oswald never became a martyr. Northumbria became lead kingdom of the Anglo-Saxon Heptarchy thirteen years earlier. Northumbria and Mercia solidified as a separate kingdom from England south of the Thames and Severn. The Kingdom of Southtames rapidly became entangled in the affairs of the Franks, where the Carolingian Mayors of the Palace were solidifying their rule over the Franks.