Celtic Toggle - Around 1st Century BC

I found this Celtic toggle on a site I have searched on and off for the last 15+ years. It is a site where the odd hammered coin pops up but mostly 17th - 18th C buckles and buttons. So finding this toggle was to say the least a very pleasant surprise. It makes you wonder however did it get lost in this spot. Had the person missed the last chariot home and took a short cut across the field, tripped over his cape and the toggle broke off. But the question remains, where had he come from and where was he heading for?