Metal slouch hat mounted on bugle sweetheart brooch

Sweetheart brooch made from a base metal (likely to be bronze, brass or copper alloy)) which has aged over time to display a dark, tarnished patina.
It features a depiction of an Australian Imperial Force slouch hat with the brim turned up on one side (as traditionally worn). This is attached on the diagonal to an elongated bugle with the mouthpiece and the bell visible at either end.
There is a pin clasp for attachment on the reverse and there are no maker's marks.