Someone must have made the decision post-Atkins that 1771 was a more accurate choice even given that the digits may not be quite following the rules. I didn't notice the G until you pointed it out. Other evasions have initials under the bust similarly though this one wasn't mentioned in my book -but the book I have is just a one chapter basic listing.
Counterfeit book should be out this month Evasions won't be covered but some of the more important families will.
Haha...18th century counterfeiters are A-ok in my book!