Are Mint Identifiers On Coins Created On Purpose?

I think the 1966 "privy marks" were intentional, deliberate changes from the master die design.

As for "why", well, the government had just spent 4.5 million pounds (9 million dollars) building a brand new state of the art high-produciton-capacity Mint building. Allowing people to easily see just how much of our new coinage wasn't actually being made in Canberra might have had people wondering if building the Mint was worth the cost, if it wasn't up to the job.

Other governments have intentionally hidden foreign mintmarks, for domestic political purposes. The Greeks are probably one of the most parochial nations in Europe. When Greece was very late to the party in qualifying to join the Eurozone, the Greek Mint didn't have the capacity to strike all of Greece's quota of euro coinage in time for the 1st January 2002 launch date. They had to outsource, to Finland, France, and Spain. The mintmarks for these foreign-made coins were tiny letters ("S" for Suomi (Finland), "F" for France, and "E" for Espana (Spain)) hidden inside one of the stars. All these foreign-made Greek coins still bore the Greek Mint's mintmark, as well as the secret foreign mintmark. Hiding the true origin of the coins this way helped assuage negative Greek public sentiment at having to rely on foreign mints for "their" coins.

Which of course raises an obvious question: if the goal was deliberate obfuscation, why deliberately put any marks on there at all? Surely the best camouflage is complete invisibility. I can only assume that desire stemmed form some kind of quality control issue: if foreign-made coins started showing up in circulation below specifications or with significant defects (eg. not working in vending machines properly), then they'd be able to trace the issue back to a source mint to seek reparations.

Very interesting, Sap. Thank you for sharing.