Well it lacks the lion passant hallmark - so that quickly discounts it from being English sterling silver. Stamped serial numbers point to plating. I can't find any sterling mark that is anywhere close to that ship hallmark - it's quite likely plated. Are you near a dealer with an XRF machine? Picture of the rest of the time would be handy. No idea what timeframe to search within without knowing if it's an 18th century sweets tray or an iPad cover.
My best guess is (educated) EPBM electro plated brass metal/base metal 100% that this is plated and not sterling