Sterling or plated

Can someone help me with a very basic question … how do I tell if something is sterling or plated is it doesn’t say EPNS?

It is made by Harrison Brothers & Howson.

The rule of thumb is: if it doesn’t claim to be silver it must be something else. Indications of silver are a hallmark (a mark applied by an independent body after assay), “sterling” (normally seen on American silver), or a numerical fineness mark such as 925, 800, etc. Your piece is not silver - it is, at best, electroplated.

Phil