This item was unearthed a few years back and the finder, Stephen Corner, was told it dated from the Viking Age and might be linked to the movement in AD 867 of what became known as the Great Army. Stephen asked for my opinion on his find.
It is made of copper-alloy, measures approximately 20mm by 16mm and has decoration on one side that is in no particular style. It has a hole at the top and might have other holes at the corners.
This will be a mount, which could have been attached to a belt, scabbard, saddle, helmet or clothing. If the find spot could be tied to the movement of the Great Army then it could be Viking. However, whilst this is a distinct possibility it is not an absolute certainty.