Thanks SMLE!
The rifle is a WW I Mark III (no rear aperture sight). It's display only (as are all their guns).
Presently it is displayed with other rifles, but as they have one case with the British Empire regimental emblems, I suggested that they move that rifle there (in lieu of an Krag-Jorgensen Carbine and Japanese Type 38).
PM sent with snail mail addy for the American Legion.