Interestingly the Daily Mail published a British Museum opinion on the Proculus coin by Roger Bland today (16th November 2012):
"But coin specialist and renowned academic Roger Bland, who is Keeper of the Prehistory and Europe Department of the British Museum, disagrees that the coin is genuine.
'I don't believe any coins of Proculus were ever made and this one is probably a 15th century forgery.The only source for our knowledge of him is a controversial history book, written at the end of the 4th century AD, much of which was made up.
It says that there were 30 tyrants who all vied for control of the Roman Empire when things got a bit messy in the late 3rd century AD and lots of people were declared Emperor. Many of these 30 tyrants never had coins made, which is a sign of a true Emperor.But in the Renaissance, when coin collecting was fashionable, people thought these men should have had coins so they made them. This coin has been made from the same dye, or mould, as another in the Munich Museum, which is widely believed to be fake.There is no context to this find either - only single coins, not hoards, have been found so their provenance is difficult to assess. Unless someone finds a hoard of these coins, I'm going to remain very sceptical that there were ever any coins made for Proculus.'"