Of course the most important thing to consider is intent. If they were struck to promote a cause or point of view then they'd have to be considered legitimate. But how do you prove or disprove intent?
I have actually dealt with the question of "proving" intent. Perhaps it helps if I tell you about my approach? The question was, how to define a long-term investment, something that boiled down to "the intention to hold on to the investment for a long time. What I did was:
List actors and analyse how well equipped they are. In this case, anybody can make them, but the British are most likely and Britons who have access to the required punches are even more likely. If the countermarked coin was purchased in say Nigeria, that says something. If it came from a UK school that teaches metal working that says something also.
List instruments and analyse what makes them most suitable. All coins can be used but e.g. those of the UK will circulate and spread the message. Circulated coins work better than proofs.
Give the two lists a generous amount of thought. Sort them by likelihood. Define a broad case of what is likely to be genuine. Test on known imitations and doubtful cases. In my case: is a tsarist railway bond partially repaid a century later a long-term investment? No. Intent to hold is lacking. The purchase of a large package of equity in order to claim a board seat is probably a long-term investment, but what if the buyer changes his mind and sells the package to a third party in a take-over bid? Buying real estate is normally a long-term investment. A day trader buying a 10 year bond is not making a long-term investment etc.
Peter