Ffion was a druid soothsayer from 1st century England.
The Fifth Doctor met her after she saved Tegan from being attacked by Romans. He became embroiled in the battle between Druids and Romans and witnessed many Druid slaughters. However, he managed to save Ffion and his friends by instructing Kamelion to disguise himself as a Roman soldier. Saddened by the deaths, the Doctor reluctantly stopped Ffion from wiping out of the Romans as it would change history. (PROSE: The Fall of the Druids)