He was a grandson of Cynric, the son of Cerdic, the first of the Saxons to come across the sea from Germany; and he and his people were still relatively out of place in a world dominated by the Britons.
The annal for that year in the Anglo-Saxon Chronicle reads, at least in part: "Here there was great slaughter at Woden’s Barrow, and Ceawlin was driven out".
Cuthwine, then twenty-seven, was a commander in the fateful battle; but upon defeat, as the rightful heir to the throne, he fled the place along with his family.
Through Cutha Cathwulf, Cuthwine's youngest son, were ultimately descended the Kings of Wessex after the line of Ceol became extinct in 685.
If this experienced prince was not the sole ruler of Wessex during the years of Cenwalh's exile (naturally in a subservient position to Penda) then it is likely that he was a member of the ruling body; but, given the tangled diplomacy of the times and his eastern power base, it is equally likely that he aided Cenwalh in his successful attempt to regain the throne in 648.
After this, he appears infrequently as a shadowy figure, apparently already passing into legend among the common people as a result of his long-held position against the (at times) brutal role of Ceol and his family.
There is reason to suggest that he was already dead by this time; at any rate he would have been past eighty by the beginning of Cenwalh's reign and it seems inconceivable that he would have lived to see the reinstatement of his line to the throne of Wessex.