The Enfield No.2 Mk.1 was made by Enfield.
If you want to shoot it, it takes .38 S&W ammo, NOT .38 S&W Special (aka ".38 Special").
Two different cartridges, but more importantly, two different diameter bullets.
Specifically, the ammo the gun shot was ".38/200", which was the S&W cartridge loaded with a big 200 grain bullet (normally, it shot a 150 grain bullet).
Nice gun. Looks like it hasn't been shot much.