According to legend Saint Patrick drove snakes out of Ireland. The problem is That the fossil evidence suggests that there never were snakes in Ireland. Most likely that snakes were a metaphor for the paganism that still flourished in Ireland. There are plenty of tales of dragons in Great Britain such as the one of St. George and the St. George and the dragon. This particular story maybe a metaphor of the defeat of winter by the forces of spring. In most tales of dragon that they guard treasures hidden in caves. One variation the dragon guards a young maiden who is being held prisoner in the cave. In these versions a knight come along and slays the dragon. Usually, the maiden becomes the bide of the knight. Again, we see this as representing a change of the season with the treasure or maiden being the return of spring. The first recorded dragon is the Babylonian Tiamat. But tales of dragons are so universal that their origins cannot be traced to any certain source. My own belief is that dragons are symbols of the chaos of death and disease that always lurks near. And so, it goes.