He lived a long life, remaining in a powerful position throughout the reign of Cynegils son of Ceol; and then Cenwalh, son of Cynegils, became king. In the year 645 Penda of Mercia overran the kingdom (in return for Cenwalh's repudiation of Penda's sister) and was for three years king, sending Cenwalh into exile in East Anglia. Cuthwine is recorded as having been present at the negotiations along with his sons, but little more is known of his activities. Nevertheless, much can be deduced. 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.