Definately a 1 Pdr or 37mm. The Hotchkiss base fuze has been replaced with a plug. As this was manufactured by just about every European country Skodawerk is no surprise. The VSM ones are always amusing as Vickers Sons and Maxim puts the same item manufactured by both sides in WW!!

From a works perspective 37mm, (1 Pdr) or even the 6 Pdr with either the Hotchkiss nose fuze or base fuze are amongst the most dangerous items of conventional ammunition that you can find. All of our people know if one is found then it is dealt with in-situ! If in doubt call the authorities, that said the large hole in the side of this one is a good target indicator that it is probably inert.