Copper-alloy annular brooch

Bronze annular brooch, diam. 5.1cm, width of ring max. 8mm. Ring of sheet bronze made with ends overlapping on one side, and here pierced by large rivet hole which goes clean through. On top of piece, hole flanked by parallel grooves. That this was an annular brooch, or possibly a buckle, suggested by fact that on opposite inner edge there is a worn depression where a pin tip might have rested.