Thanks for the link Jedi. I'll get the hang of this interweb thingy one day!
How this event originated is now lost in the mists of time. I think it's a pretty unique event these days. Although a couple of other little places still roll barrels through there towns, here in Ottery st, Mary, where men are men and sheep are scared, they pick 'em up and run through the crowds with them on their shoulders.
Theres also womens and boys barrels earlier in the evening. The last barrel, in the town square at midnight, is big enough for a grown man to cower in!
I think it's just another excuse for a winter festival with drinking and general mayhem linked to, historically, this being a big cider producing area!