I've had several die varieties in this series which Colin Cooke didn't have examples of; I don't think he was greatly interested in the series. There's a prejudice going back all the way to Bramah that these die variations are so numerous that they are not of interest to collectors; of course, if you applied the same thinking to the bun pennies, there would be no Freeman, Gouby etc. The reality is that this series is notoriously underexplored; you can get £50 or £100 for the more interesting die varieties in nice crisp grade, but not many people appear to be after them in circulated condition right now.