 Berkshire appears to have passed out of Mercian hands and become a part of the kingdom of Wessex at some point during the late 840s . In 844 Ceolred , the bishop of Leicester , granted Beorhtwulf an estate at Pangbourne , in Berkshire , so the area was still in Mercian hands at that date . Asser , writing in about 893 , believed that King Alfred the Great was born between 847 and 849 at Wantage in Berkshire . The implication is that Berkshire had previously come under the control of Wessex , though it is also possible the territory was divided between the two kingdoms , possibly even before Beorhtwulf 's accession . Whatever the nature of the change , there is no record of how it occurred . It appears that the Mercian ealdorman Æthelwulf remained in office afterwards , implying a peaceful transition . 
