A recent post on Ancient Coin Collecting about the ongoing conflict between 'cultural property bandits' (that could be you, world coin collector) and archaeology. http://ancientcoincollecting.blogspot.com/2010/10/yin-and-yang.html
Two weekends ago, my wife and I went to the University of Michigan museums. In the archaeology museum, they had displays of ancient coins which the placards admitted were without provenance. I took a picture with my cellphone and sent it to the ACCG. Wayne wrote back that it is not unusual for museums to display material that lacks attribution and therefore the claim by archaeologists that collectors degrade the opportunity to do proper recording of discovery is fallacious. My favorite is challenging a "cultural patrimony" advocate to tell me which national museum has a right to a Roman coin, struck in Constantinople, found in England.
If you put the emphasis on "museum", the answer is fairly simple - some place in the UK. The problem or dispute is usually about private collectors, and where/how they buy coins. Here in Germany for example selling or buying an old coin without a certificate of provenance is not illegal. But especially when you buy ancient pieces from some eBay seller who can or will not provide a "pedigree", there may be investigations which can be time consuming and even intimidating. Christian
Well, yes, museums acknowledge each other so graciously. No provenance? No problem! But let a private collector fail, and someone wants to enforce a law. (The word "graciously" appears only once in the composing box. Interesting glitch.)
The idea that "private collectors" are the bad guy is pervasive in the world. And it's been that way since the days of Carter, and no I don't mean Jimmy either. Our films, our books, our literature, has always portrayed the "private collector" as the guy who tries to buy, usually surreptitiously, just so he can have it all to himself as opposed to putting the object in a museum so the whole world can share in enjoying the object. The problem is one of perspective. And that perspective has been foisted upon us since long before any of us were ever born. And it will never change. That's a simple fact of life. I'm not saying that makes it right - just saying that that's the way it is and we as collectors have no choice but to deal with it.
If a museum today wanted to purchase old coins (according to the Unidroit convention, "old" means 100+ years, I think) from undocumented sources, it may run into similar problems. But in the case you mentioned - of the coin found in England etc. - I assume that this "pedigree" is easy to provide, whether it is legally required or not. And that is why I wrote that the answer is simple in my opinion. I am by no means an expert when it comes to these matters. But my impression has been for quite a while that we have "extremists" and very shrill comments on either side. Christian