Antique British Military Whistle in VG Condition - Late 1800's

Actual age or metal composition unknown
I sent photo's to an antique whistle dealer and he responded that this is a british military whistle that would be mounted on a chest strap, possibly mid to late 1800's
I also took to a local jeweler to have tested for composition, it is NOT sterling , jeweler did not state what metal it is though.
VG condition as pictured, FL garage sale find
2.75"L not including eye ring for chain ( Chain NOT included )