After such a long period of time, it's been disconnected from the context in which it was made - all we can really say about it really is that it was privately engraved. It would have had to have been someone with a steady hand and good eye to do such a neat job on a tiny coin like a threepence.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis