The appearance on the market of increasingly sophisticated forgeries should be a source of concern to all collectors, not just those of Henry III. This article describes four forgeries of Henry III pennies, and advises caution when considering buying coins being sold from Eastern Europe.
Caveat Emptor: Some Modern Fakes of Henry III Long Cross Pennies – Rob Page
BNS Research Blog 
Good article Rob. I think provenance is only going to get more important as technology allows the production of more and more fakes. I know I’m reluctant to spend serious money on coins with no provenance and I can see a time that I won’t buy any coin without provenance. Auction houses and dealers may have to change their practices to address that trend. I have quite a few really nice Henry III long cross pennies but most can be traced back to Lockett which gives me assurance.