Here is some old 9.5x57 M1910 Mannlicher-Schoenauer aka .375 Rimless Nitro Express ammo from my collection, top to bottom:
Kynoch box, code 12 I S
cartridges,l-r: Kynoch solid, Kynoch soft nose, base stamp "KYNOCH 9.5mm MS", pre-1940 DWM K soft nose, case # 531
Eley package, code stamp ME M X. Don't know what the cartridges look like because the box is still unopened.

Any idea how old the Eley box may be?